If you've done a bunch of them and have a good hard work area and a way to lift the tractor, yes, 20 minutes. Having a loader makes it a little easier. A TLB is really easy. Lift the front with the loader bucket, the rear with the outriggers.
For everyone else, an hour.
Assuming the fuel is clean when it's put into the tank, and assuming that the tank has no debris in it, the filters should never need to be changed. But those are two big assumptions. Have seen them go hundreds of hours on some, and 10 hours on others. Lot of it depends on how good the fuel is that's going into the tank. Sometimes the jugs have stuff in them that you can't see. Sometimes it comes out of the pump at the gas station dirty. Sometimes a leaf drops into the tank while filling, and sometimes grass/mud/dirt gets into it while the cap is off. For those cases, that is what the fuel filter does. Protects your engine (pumps) from contaminated fuel.
If you suspect that there's stuff in the tank, pull the tank and flush it out real good. That in itself is a bit of a chore. I always suggest filtering the fuel before it goes in on the BX's because of the inconvenience of having to change that rear fuel filter and/or pulling the tank for flushing.