As much as I feel like it, and never with guilt. I've hit over 7-10 times in a day many times, and I'm 33 years old at the moment.
There are days where I'm depressed or going through things (like a hangover, haha) where I just don't feel like it, so I don't at all. There are others where I'm just jerking it until I'm raw all day long. If I feel like I haven't done it in a couple of days, I'll often just go ahead and do it in the same way that a person might decide they should probably eat something just because the timing says you should, even if they're not hungry …. I want my body to continue producing the hormones that make me want to ejaculate.
The people who only go once a week boggle my mind, but I think it's possible for anyone to get there if they let their sex chemical production die down (they're letting their lives distract them from the majesty of cumming, so they stop seeking it out, which leads to the body producing less testosterone which makes you want to cum less ... self-feedback loop kind of thing). Frankly, I love sex and want to FEEL horny, so I don't want to evolve to that state. I don't actually sit down with a spreadsheet and crunch numbers or anything, but if I'm not averaging twice a day at a minimum, I'll probably start getting morose and will eventually devote half of a weekend day to drowning myself in my own cum and precum. My foreskin gets so tender after those 8-hour marathons, but it's the good kind of burn ... like after a workout or really good spicy food. :cheers:
Of course, it's much more fun with a partner (a good bottom, preferably) to milk that cum out of me with his orifices, but that's not always possible.