I think you can do it as often as you can manage. No harm from it.
I don’t think you have anything to worry about. The fact you function this well at 50 is a sign of excellent health, obviously no ED at all. Generally your body will let you know when you’ve had enough, so as long as you both have the desire, there’s no need to slow down. Often couples in new relationships have some fairly intense & frequent sex. This may taper off a bit as the excitement level falls off a bit, and if that happens, it’s no indication anything’s wrong, it’s fairly normal for that to happen. I think frequent sex at your age is only a good thing - I see no downside to it all. Keep it up - pun not intended, but now that I think about it ... LOL !!