I check my solution whenever I feel like it.... at LEAST once in 24 hours... but usually several times a day. I'm a fan of the stronger stuff too... remember girls!!! always adjust with your pump off.... dont wanna f up the ph in your wool.
I chose never, although that is not entirely accurate.
I only adjust when the nute mixture is very low (right at the start) and ph tends to drift on the high side.
However, I use buffered nutes and at anything above 250 ppm you are fighting a useless battle. The Canna buff's out at 5.8 consistently and has done wonders. The times I have had trouble is when I've tried to 'fix' a problem that wasn't there to begin with.
Well, I just converted to hydro yesterday, but I plan to check the pH every day. During veg, I'll keep my pH in the 6.0-6.5 range, and when flowering, I'll try to stay between 5.6 and 6.1
The pH of my ebb and flow system adjusts itself every day when I add two gallons of freshly mixed solution to an 18 gallon reservoir. The renewed solution keeps the pH right where it should be. Of course, having never measured it in my life, I can't swear to that, but my plants are healthy as can be and growing like crazy.
I voted as "Every Day" because that is exactly what my system does by it's transpiration rate and my adding new solution each day.