Plan the minimum connection time between flights.
A safe connection is the sum of the steps between one aircraft and the next, and walking between gates is usually the smallest of them. Immigration is the largest and most variable, security re-screening applies whenever you leave the sterile area, and baggage reclaim and re-check is required on many itineraries that are not through-checked. A terminal change adds around fifteen minutes for a transfer bus or train. The safety buffer then absorbs the inbound delay that is the actual cause of most missed connections.
Minimum connection time
Minutes = gate walk + terminal transfer + immigration + security re-screen + bag re-check + safety buffer
It depends on the route. Connections through the United States require it on every international arrival, as do many itineraries where the transit area is not sterile. Within Schengen or on a domestic-to-domestic connection you usually do not — set that field to zero.
Not if they are through-checked to the final destination, which is normal on a single ticket with interline agreements. Separate tickets almost always mean reclaiming and re-checking, and that is when the bag figure matters most.
It is the legal minimum for rebooking protection, not a comfortable plan — it assumes an on-time arrival and no queues. Booking below it forfeits protection; booking at it frequently means running.