If your distributor is engineered, you can get away with three medium mining lasers in a Python.
Forgive my total ignorance and assumptiveness, but I'm understanding the advantage of mining turrets is that they will converge, am I right? So if that is the case, does having 3 mining lasers drill rock faster than 2? Because you can't target the astroid right? I really haven't touched mining since like pre wings/cqc and that was for about 15 minutes before I swore never again