This is mentioned in the linked forums & blogs, but one thing I wanted to call out at a top-level that made a big difference for fractional beeminding for me was the realization that as long as you have a bright line for what counts as “1” and so never get more than one total point per painting, it doesn’t matter how good at estimating you are. Maybe you thought you were halfway through, did the same amount again, and realized your first estimation was totally wrong: no stress! 0.5 for the first chunk, 0.2 for the second, and everything is fine.
To elaborate on the learning to paint example, you could assign 0.2 to each of research, choose paint, buy equipment, start painting, finish painting. But maybe you have a hangup about actually starting the painting, but know that once you get going it’ll be pleasant—you could count 0.1 for each of research, choose paint, buy equipment, and finish painting, and 0.6 to start the painting. Or you could plan to have them all be 0.2, get to the starting and realize it was super hard, and give yourself 0.3 for that, saving the last 0.1 for finishing.