Prague has four terminals (A, B, C, D) connected by walkways. Longest distance from say A8 to C11 depending on your physical condition is about 12 minutes. There is a delay when you come in from outside Schengen (A,B) and you want to go into Schengen (C, D). In that case you have to pass both customs and security. The other way round both don't happen - security check in A and B will be at the gate. OK does its best to have connections succeed - unfortunately to the point of delaying a full plane. But if the connection is particularly tight an OK employee will be waiting when exiting the pane and directing you to the departure gate of your connecting flight.

But I would not count on connecting too speedily when using some LCC as you will have to collect your bags from the belt and check in again - which might easily cost you 70 minutes or so. Most LCCs do not have agreements with otrher airlines about luggage handling.