It’s been 5 years since my last rated game. I only play lightning or blitz occasionally on chess.com and lichess.org nowadays.
(And I STILL cannot consistently spell “occasionally” correctly the first time).
On days that I feel particularly sharp or dull, my chess performance seems to reflect it. So on days when I’m just not sure about how well the brain will function that day, I play a few games to figure it out.
Of course, this method does have some problems:
1. Do I selectively remember those days which support this hypothesis?
2. Did I control for the strength of my opponents?
3. Is my sample size even big enough?
4. [Other stuff I’m not thinking of]
Naturally, the answers for 1-3 are probably “yes”, “no” and “no”, but the hypothesis sounds good enough to me.