From my experience, post transfers can be done on a lot of games, and other games it's not so easy. However, each game is different. You could post transfer really easily on one game, and not be able to on the same title at a different location. I can post transfer really easily on my Whirlwind and X-Files, but it's a bit more difficult on Meteor. Sometimes the geometry of the game and where the posts are located makes it more difficult.
On some newer games, what you can do is shoot a ramp which will return it to the other flipper. Like T2 for example. If you want to hit the skull shot, but it's cradled on the left flipper, hit the right ramp to get it to the right flipper. (The skull shot is backhandable, but for discussions sake, we're hitting the right ramp.) Same with AFM, shooting either ramp will return it to the opposite flipper. And with each ramp shot you are actually progressing further into the game.