Are checked luggages usually checked once for a connecting flight?

It used to be when you booked with a single airline that had two connecting flights that your checked luggage would automatically be checked all the way through to your final destination but some airlines are changing that, in some cases because they get to charge you for a checked bag on two different flight segments. Since you don't give any details of whether this is with a single airline, an airline and one of it's code-share or flying partners, or with two entirely different airlines with no business relationship, it's hard to give you specific answers. Check with the airline(s) you booked with - there should be a toll-free customer service number you can call to be sure.