I think that in some cases, large ISR tasks make sense. But, ISRs by nature occur at times not known at compile time, meaning that the longer an ISR runs, the l

I think that in some cases, large ISR tasks make sense. But, ISRs by nature occur at times not known at compile time, meaning that the longer an ISR runs, the less you'll know about system behavior at compile time. So, if you know that you need a long running process triggered by an ISR, that's fine, make it so; but as a general rule of thumb, the shorter the ISR, the more deterministic your system is. Those ISR runtimes need to be designed to be good fits for the system, or they can cause problems.