I write software. In my job I frequently run into times where I'm unsure how to best proceed. I've learned that, personally, I can often solve this by taking a quick break and walking around. This usually entails getting away from my monitor and taking a 5 minute walk outside. I know when I'm blocked this way, and I can spend hours staring at a screen or piece of paper without progress, but after these short breaks I will often sit down and be able to immediately write a good solution. I do this every hour or two.
I've run into this problem in whiteboard coding or online technical phone screens (coding in a shared IDE or whatever). I "lock up" and can't really proceed, and I'm not producing a useful stream of thoughts. I know staring at the code I've written is futile and I won't be able to find the bug or optimize my solution or whatever without a short break. However I think it's unreasonable to ask the interviewer to be on hold for 5 minutes while I go take a walk.
Is there a reasonable compromise to be had here? It can be very frustrating, especially if I struggled with a tricky problem and then find a great solution on my walk 5 minutes after hanging up.