I would like to suggest a "Project Limit" feature like World Community Grid uses. Please see the attached screenshot:
I think it makes sense, in order to avoid e.g. the download and the calcultion of several SoB tasks at the same time. It would help to manage the priority of tasks.
For the Tour de Primes it could help so you download only one task for the CPU and one task for the GPU at a time and not e.g. two tasks for the GPU where one task needs to wait to be calculated.
I think this would be a good addition to PrimeGrid.
Thank you very much,
My lucky number is 113912436^65536+1