I have elevator and aileron trim set to 2 separate axes on my throttle quadrant. I use them quite a lot. Not so much for minute tweaks during combat, but for general flying. Taking off I know the "feel" of where they should be for the average plane. For climbout I pitch down from that a bit and ease up on ailerons. For formation flying I like to tweak them to get hands-off (sometimes) formation flying. I have pedals but also a slider for rudder trim. It's just not as easy to get to without taking my hand off the throttle (it's on the base of the stick).
If I take ord and drop one, have a single bomb or single DT, or even if I manually drain one wing tank to compensate for torque then manually switch to fuse tanks, I can compensate for the weight. When I come in for landings I leave CT off and trim for nose-level while popping flaps so that I can come in nice and smooth. CT will often pitch you up or down depending on the plane when you pop full flaps.
Overall it's really really not needed, but I have the extra levers so I mapped them and like it.