About once in every 7-10 days.
I could do more often but I just leave them grow for a while, because for me it is also important to be able to cope with different circumstances that includes slightly different nail lengths. We all try to avoid accidents but they do happen nonetheless. I have to be reasonably prepared for the accident.
I often start off my day with guitar daily workout for 1/2 hour (because the first 2-3 hours of the day are crap if I work), and which includes some flamenco picado (fast I-M picking) and pulgar (P finger fast playing). My picado gets slower when the nails gets longer because they catch strings more. Likewise the pulgar.
When this situation has taken place, I start thinking when I did the nails last time
then if it is more than 7 days before, then I go "yeah I thought so... let's do the nail AFTER the workout" and keep working out for the 1/2 hour, then do the nails.
There are some other benefits, in particular you will experience various modulation of the tones at different nail lengths some of which you might like and incorporate in your performances. You cannot expect this if you do your nail perfectly everyday or every other day, without making any mistake. Here we draw on our imperfect nails.
Fortunately my nails have been strong enough, so I do very little compared to some other players. I just clip the excess and file it with the file on a clipper, then rub the edges with my leather waist belt. Occasionally I use a strip of 1000' sanding mesh for some minor touchups, as there are perceived (and not measurement) imbalances of nail lengths, especially between P nail length and the other nail lengths, sometimes affect my performance, and it's nice to have the strip handy instead of a nail clipper.
I hope this handier practice example helps you.