Well, true. I wouldn't ever suggest just constantly drawing personal art.
But even just doing a ten minute sketch does help rejuvenate the 'inspiration' that seems to deplete when doing commission work.
Never mind that commissions are stressful, and that stress can make you doubt your art... 8| And then wheee the quality goes down.
I know, at least for me, what usually roadblocks me on commissions is getting stressed out that I'll do a shitty job and not give them commissioner what they want.
even if most of the commissioners that have commissioned me are overly vague in what they want. B|;;
Of course, I'm working on getting over that fear/stress anyway. Hard to do, but I'm working on it.