How many buyins should you keep in your online account? Learn in this video. That is only a fraction of what bankroll management is though. You will gain all the necessary tools to successful sng bankroll management in this video.
The recommended style works in all types of sngs when used properly. From your comments above it sounds like you haven't played a large sample size yet. To compare two different buyin levels and your ROI at those levels you need to play thousands of games at each level to have a large enough sample size to make an accurate assumption that you are better at one level.
So I recommend playing within your bankroll and eventually the luck will even out. You want to play with weaker players. If you play with all winning players it won't be a profitable game.
Bankroll management for HU sngs is very similar to 6 max sngs. It will vary quite a bit player to player based on your roi. You can keep slightly less buyins though for HU sngs than 6 max sngs imo.
A lot of mtt players use a 100 buyin rule but I think that is too risky for large field mtts. Even great mtt players go on 100 buyin downswings due to variance. If I were grinding mtts every day I would use approximately 150 to 200 buyins for mtts with 1000+ players.
Is there a printable version of the table somewhere on the site?
Thanks,
JG