Transformers are complex gems when it comes to toys, it is fun making something turn into something else. There has never been an incident where I completely forgot how to transform a figure, there have been the occasional steps.
Cybertron Unicron: I forgot how to get the arms into vehicle mode and thus snapped one of them off at the hinge thank to my stubborn refusal to reference the instructions.
RID Landfill: Combining is simple with Grimlock as the arms, but since I rarely put him into his other two arm configurations I had to reference the instructions to get Hightower into the arm mode.
There are probably others, but since i haven't pulled any of the older stuff out of storage recently, save for RID, I can't really comment on them.
That being said however, I can go five years without touching a toy and once it's out of storage I'll still remember how he transforms, it's partially memory, but I think muscle memory might play a small part of it too. Your hands just know where the pieces go to make the robot.
Even when I had them I didn't have too much trouble with the Alternators, but I still didn't like them because they were more complex than they needed to be IMO for plastic toys. Well engineered, great for display, but no fun to play with.
