Then rejet bro.
I check my plugs on almost every ride. So, I'll rejet when it's necessary. Now, just because I check plugs often, doesn't mean i'll change jets very often. Maybe only 2 or 3 times a year, or if I feel I've moved in elevation enough or if it feels like it wants it.
Generally, as the winter season comes in, I'll notice the plugs leaning a little or maybe a little hesitation to start off with, so I know it's time. There's no rule set in stone, jetting is reading, feeling, and knowing your machine. I know how it's supposed to be and I know when it's not how it normally is, so I know when to react. The jets in your carb are the lifeline to your motor, that's why I'm always checking plugs and am not afraid to just go ahead and throw another size in if I feel it needs it.
Remember, worse thing you can do by richening it too much is maybe foul a plug, it's much much worse to ignore it and end up lean.