Routine labs

Hello,
I was just wondering how often you check routine labs? Like TSH, Dilantin and Valproic Acic levels. I am not talking about patients just starting on these meds, but long term, stable patients, who have been taking the meds for awhile. Also, what about labs pertaining to med use, like LFT's. We have some Dr's that order them routinely, and another Dr. that said "that is up to the facility to decide, unless I tell you otherwise." Well, we don't have a set schedule or protocal for when/how often. What does your facility do?