Thanks for the replies so far.
@gotten: Yes well, it is all a bit difficult because it is also correct that not all requests are that "bad".
A repeat would be a request where you set an arbitrary number and combination of frames, and instruct the system to repeat this x times through the night, with a configurable interval between single "repeats". This is a function which is convenient for both astrometry and photometry.
Now, imagine somebody requesting a 10 second exposure of a variable star, every 20 minutes. With slewing and all overhead, whis would effectively block the scope for any request longer than about 10 minutes, which could fit in between the single repeats.
In your case, if you combine any amount of exposures in one go this would not apply 🙂
I agree that it all sonds complicated, and maybe for real photometric work with plenty of short exposures one after the other we shall find a better solution as to not penalize it. This is one of the reasons I want to discuss this openly. The easiest would be a simple "fair use" policy, where every users agrees to not try to trick the system to a disadvantage of others.