100 days is probably a pretty good limit, it starts to lose effectiveness past that. Last year I did 234 days straight, only ending the streak on my wedding day, but it should have ended much sooner. It was ultra-productive for the first 60-70% of the days, but the focus started shifting from being productive to keeping the streak alive. It ultimately became counter-productive after going for so long. Sounds great in theory, but make sure you give yourself a hard limit.