Unfortunately the Blue Prism schedular is this basic "Start Process 1 at Time x, Start Process 2 at Time xb" product that was created many, many years ago and never improved to have any intelligence. Active Queues was intended to fix it but the full design for it was never implemented leaving an unusable half product, I understand the smart guys in the BP product team are looking to make the browser based control room do some of this smart stuff very soon.
Instead of thinking in the way the old Blue Prism schedular forces you to think, I would encourage you to think like a team leader would think. Imagine you had a team of 10 people and a variety of different work that can come in at different times of the day and that have different priorities. If you got a rush on a type of work that was of most importance you would take your people off lower priority work to clear the backlog before putting them back onto the lower priority work.
You therefore need to think differently with your robots. You need all your robots to be running and waiting for instructions about which process they need to work depending on what work load is available and the SLAs for that work and the approximate time it will take to complete the work.
Unfortunately the Blue Prism product does not do this for you yet, the lack of such a basic functionality in a work tool is why the RPA Supervisor product exists. There are some good examples of how you can do this in the Digital Exchange, one of them is called 'Process for Dynamic Resource Manager' there seems to be others on there also including the one from SmartRPA.
What you have been trying to do is correct because it is where the product currently takes you, but it is not scalable, it is not how managers would manage work, and it will lead to poor utilisation of your robots (for example, if you schedule a robot to do work for 1 hour and it completes the work in 5 minutes, you have 55 wasted minutes until the next schedule starts).
