That’s what happen when people started knowing you for your good work results, which is getting better day by day.
Only you have sole authority to decide, whether you will do it for Free or you will charge for a specific task.
Charging or no charging for a work doesn’t depends on the quality of work result. But quality matters when you start putting a price tag on the work.
I mean, you don’t give it free just because it is just an ugly sketch.
Sometimes, price also depends on the urgency too, once you gets into the work Professionally.
Still, to my experience, we all get paid for solving specific needs.
In design work, sometimes designer may not feel the work she has produced, but customer is willing to pay, as long as she is happy with the result. Even if you give it Free, customer may not want it, if that doesn’t help solve her problem.
You have just opened a new door to learn by not doing free works.