But how long would it really seem? Presuming your brain doesn’t reset as part of a time loop but rather you continue experiencing consciousness but are forced to keep trying the same thing, it would reach a limit at some point.
Supposing you can try variations always to the same goal, there will still be a finite number of different possibilities. You will forget exactly how many times you repeated each particular variation, and in any case repeating doesn’t lead to new memories once you’ve memorized it. So, doing it a million more time would not seem to be any longer than when you thought about it before, right?
Or there might be limits in the brain’s subjective memory capacity.
Using whatever mechanism you might consider, what would the subjective time span of eternal repetition be? Or, can you repudiate that and suppose that the mind changes in other ways, but I think that leads to a larger limit, not a lack of any limit.