Our charter specifically says they want parents to drop off/pick up their children in order for them to be accessible to the teachers and vice-versa.

Recently, my husband and I had a question about the class procedures and requested (by phone message) a convenient time for DS' teacher to meet with us. She asked us to come to the school fifteen minutes before class.

We came with DS and while he got ready for his day (sharpening his pencil, etc.,) we talked with his teacher. It was comfortable for us.
But if we had had a larger issue to discuss, perhaps right before the beginning of class wouldn't have been optimum. We would have requested more time at her convenience.

But this is our charter's way of doing things in general, I believe. They really emphasize the parent/teacher connection. The school expects parents to be an active participant in their child's education. (And states so on their website.)