I'm confident once per day is too much, because then you'd be doing it pretty much whenever you wanted and you wouldn't know if you're addicted to MO or not. Besides, doing something potentially addictive daily is a bad idea, really. However, once per week seems infrequent to me, so on balance, I think that three times per week is probably what I would say.
I would add though, that for nearly all men MO of any kind during a reboot is bad as it's basically impossible to do it in a healthy way. YBOP says some older men can do this. I'm just over thirty and I can't do it. I can't MO to sensation most of the time because i'm desensitized. Sometimes, when i'm super aroused from being part way through a reboot I've done it, but I don't think this is healthy. It's super stimulating and kind've like combining premature ejaculation type response with desensitized response to get a resulting response that can't be good.
So unless you're significantly older than me, my advice is def to avoid all M during a reboot.