Allow work patterns to have a certain number of hours per week without those hours being allocated to certain days

At the moment work patterns must allocate hours or days to specific week days.

Instead of this, it would be great to be able to add hours or days to a 'pool' for the week to be used on any day. This way we could track the correct work pattern on a query but still have the flexibility and ensure holiday functionality works with the flexible pattern as well.