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Maximising slack RRS feed

  • Question

  • I've had a rummage around previous posts and can't find much on this - please point me in the right direction if this one's already been dealt with.

    I understand MS Project's calculations are intended to provide maximum utilisation of resources. So, if a project is set to schedule from a 'start date' the work will be completed as quickly as possible - regardless (say) whether or not a business driven deadline is weeks away. 

    Conversely, if you schedule from an 'end date', MS Project doesn't start the work until the very late so as to maximise resource utilisation.

    What I'd like to be able to selectively do however is absolutely maximise slack for tasks except for activities that genuinely are on a critical path. So, if the project has to be delivered by the end of the year, I would like to create a plan that allows resources to commence at their discretion across a very wide date range. Not one that is being cut back by Project's single mindedness (!) in keeping the resource pool fully occupied. 

    Is there a way of doing this please? In case you were wondering what the logic behind this was - I'm trying to find away to give resource brokers the maximum possible flexibility in a matrix organisation.

    Many thanks in advance.

    Wednesday, August 20, 2014 9:10 PM

Answers

  • BarnD,

    I'm not sure where you got the idea that Project has a "single mindedness" to maximize resource utilization, but it's not true. Matter of fact, we have had several posts wherein the user wants a way to maximize resource utilization.

    It sounds like what you need in your plan is fixed duration tasks. That allows you to set the time periods during which each task is performed, assign resources and Project will linearly spread their work over that time period. You should of course, link the tasks in a logical sequence such that you will have a dynamic schedule and also be able to review and manage the critical path.

    Hope this helps.

    John

    Wednesday, August 20, 2014 9:50 PM
  • Hi Barn,

    Smiply add a milestone with a must start on constraint at the finish of the year. You will notice that slack becomes huge just as you want. Start time shown will still be ASAP but the freedom you request is in the slack. It may even be clearer if you also show Late Finish!

    Greetings,

    Thursday, August 21, 2014 8:05 PM
    Moderator

All replies

  • BarnD,

    I'm not sure where you got the idea that Project has a "single mindedness" to maximize resource utilization, but it's not true. Matter of fact, we have had several posts wherein the user wants a way to maximize resource utilization.

    It sounds like what you need in your plan is fixed duration tasks. That allows you to set the time periods during which each task is performed, assign resources and Project will linearly spread their work over that time period. You should of course, link the tasks in a logical sequence such that you will have a dynamic schedule and also be able to review and manage the critical path.

    Hope this helps.

    John

    Wednesday, August 20, 2014 9:50 PM
  • Hi Barn,

    Smiply add a milestone with a must start on constraint at the finish of the year. You will notice that slack becomes huge just as you want. Start time shown will still be ASAP but the freedom you request is in the slack. It may even be clearer if you also show Late Finish!

    Greetings,

    Thursday, August 21, 2014 8:05 PM
    Moderator
  • I think you will also be better served creating a project prioritisation process. If a project has 6 months before it's needed, then its priority should be low and its start delayed. The closer its delivery date gets the higher its priority.

    It's much more efficient to start and finish any task or project in one go so you don't want to start it and let it dawdle over 6 months or more. Once you start it, finish it, but don't start until the scheduled delivery date s about a month before its needed.


    Rod Gill
    Author of the one and only Project VBA Book
    www.project-systems.co.nz

    Thursday, August 21, 2014 8:18 PM
    Moderator
  • Hi John - thanks very much for taking the time to post back. I think it was in some MS Project CBTNuggets that I did quite a while back. Steven Caseley is the guy in question and if memory serves his position is that the MS Project scheduling algorithm first tried to complete the project in the shortest duration possible and all other things being equal will try to maximise resource utilisation. In day to day usage the actual execution may not be quite as clear cut.

    I will have a play with the fixed duration idea - thank you.

    Thursday, August 21, 2014 8:39 PM
  • Thanks Jan - that just might do it. It feels a bit sneaky(!) but if it produces the result that's just fine by me - thanks again.
    • Marked as answer by BarnD Thursday, August 21, 2014 8:54 PM
    • Unmarked as answer by Julie SheetsModerator Friday, August 22, 2014 5:13 PM
    Thursday, August 21, 2014 8:41 PM
  • Thanks for taking the time to respond Rod - I agree in principal but it's a slightly weird use case. I'm facing a situation where discrete activities need to be complete and tracked and resource brokered in a matrix environment with some very busy teams. I'm trying to give them as much leeway as possible to do the jobs as 'fillers' with whatever spare time they can find.
    Thursday, August 21, 2014 8:45 PM
  • BarnD,

    I think that you may have mis-interpreted that bit about "maximise resource utilisation". MSP doesn't do that.

    What it does try to do by default is get the tasks scheduled to happen as early as possible, so that the duration of the project is as short as possible.

    If you have a task with a duration of 1 day and assign a resource to it with 4 hours of work without specifying when during the day those 4 hours should occur, the default assignment is for the first 4 hours, which is a perfectly reasonable default position in the absence of any other instruction.

    If you have a task which has an estimated duration of, say, 10 days and has nothing stopping it from starting today, and a resource who is assigned to it and is available today, then the task should be scheduled to start today. This does not mean that it will or must start today. The resource may choose or be forced to start it next week. If you ask him at the end of tomorrow how its going and he says he hasn't started, then you will re-schedule it to the next earliest opportunity, which is the day after tomorrow. So the task keeps on being scheduled to happen as early as possible and then keeps on not happening as scheduled and then being re-scheduled. Whether there is any significant consequence depends on whether it is holding something else up, whether it is already on the critical path, or how close it is getting to it. If you are just burning the float/slack and there is plenty of it, then no problem. This is why it is very important to have a very complete network opf predecessors and successors, so that the consequences of delay and re-scheduling are readily apparent. There is no point in stressing out over things which don't matter but also risky to be unaware of risks which do matter or very soon will.

    Friday, August 22, 2014 12:55 AM
  • Hi,

    Doesn't that mean my reply is the answer to your question? So would you mind amrking it as answer? Thanks ahead.

    Friday, August 22, 2014 1:23 PM
    Moderator
  • Jan,

    He already did, yesterday.

    John

    Friday, August 22, 2014 2:50 PM