My doctor will raise it if I ask and if I'm healthy enough after 3-6 months of the current dose. For example, I could raise my dose now, except my bloodwork shows I need to get my thyroid checked out by my GP, so she said once I schedule that appointment, THEN I can raise my dose. She bases it mostly off of the changes you experience.
In general, if you're in good health, my doctor starts you off at a half dose, raises it at 3 months to the full, and then if she and you agree you need or would feel better, she will raise it to 3/2 of standard after 3-6 more months.