That’s a more meaningful prefix than “,” at the expense of a couple more key strokes. I consider that to still be a win in the book of tab completions.

I would replace underscore with “-“ or “.”

I used to use "do" as a prefix e.g. "doBackup"

Nowadays, I tend to skip using a personal prefix and just try to name commands with a suitable verb in front (e.g. "backupMySQL") and ensure that there's no name collisions.

Whenever I see "my" as a prefix, it feels like such a childish "my first Sony" thing. I hate official sites using that.