There are a number of factors in play here:
- Effort conversion factors
- Project schedules
- Resource schedules
- Stuff I forgot :-)
Effort conversion factors are the numbers OmniPlan uses to convert the units we use (minutes, hours, days, weeks, months, years) into the units it uses (seconds). Effort conversion factors apply to the entire project, and are set in the Project : Unit Conversions inspector.
Project and resource schedules tell OmniPlan which hours it can use to schedule activities. The project schedule (set up in View->Calendar View or the calendar view tab) gives the working hours for the project. Individual resources may have a schedule which restricts them to a subset of the project working hours. For example, a busy factory might run production in 3 8 hour shifts each day, 6 days a week, but an individual worker would have a resource schedule that only assigned them to 1 shift per day.
In your sample file, you've got project working hours of M-F 8-5. You've set your slow cooker resource's schedule to be 24x7, but that doesn't have any effect because the project schedule is more restrictive. Here's how it looks after I set the project schedule to also be 24x7:
That's looking a little more like it (though the durations are much longer than any slow cooker recipe I've encountered). The chef comes in on the first day, preps the food, throws it in the slow cooker, where it stews for a bit more than 1 full day, and it is ready to eat in the latter part of the second day.
However, look at the duration figures: "3d 6h" to cook, yet it is finished on the second day? That is the effort conversion factors making their presence known. You have a few options here. You can try to adjust them to some value that makes sense, or you can dispense with them. You could set the conversion between days and hours to be 1d = 24h, which would make sense for the slow cooker — "this needs to cook for a day" presumably means it needs to cook for 24 hours in an environment where you could around clock. On the other hand, if you assign a task to a chef and tell OmniPlan it will take a day, you presumably mean a typical work day for the chef, not 24 hours, right? Easier to just refer to and display everything in hours, I think. You can achieve this by bringing up the Project : Formats inspector and unchecking the boxes for the undesired units (days, weeks, months, years) in both the Effort and Duration columns. After doing so, the diagram looks like this:
The final question is effort vs. duration. You said that preparing the ingredients would be 2 hours, requiring both the chef and the kitchen bench. Your diagram shows a duration of 6 hours and effort of 12 hours, but let's use the 2 hour figure you mentioned. I would use the inspector to clear the resource assignment, then set duration to 2 hours. Normally, OmniPlan would assume that adding resources to a task cuts the duration but maintains the effort: 1 person takes 2 hours to chop the vegetables, or 2 people get the vegetables chopped in 1 hour, but 2 hours of effort are still expended (1 by each person). However, in this case, adding the table isn't going to make the chef chop any faster (if he doesn't have the table, he'll use the floor, right? :-) so we want to tell OmniPlan to hold the duration constant when adding resources. There's a radio button in the Task : Assignments inspector to control whether effort is fixed, duration is fixed, or both when assigning resources to the selected task(s). Set duration to be fixed, then assign the chef and the equipment. You would probably want to do the same for the "serve dinner" task, but in your sample you've only got one resource assigned, so it isn't noticeable.
Here's the final result, with a view of some of the inspectors used:
Are you really planning to use OmniPlan to manage kitchen activities, or is this just an example for learning purposes? I've used it for planning the preparation of some elaborate meals that took me a couple of days in the kitchen. Some might think this a trivial application of the tool, but I'm in good company:
Some people have a foolish way of not minding, or pretending not to mind, what they eat. For my part, I mind my belly very studiously, and very carefully; for I look upon it, that he who does not mind his belly will hardly mind anything else.
James Boswell: "Life of Johnson"