APL really encourages code golfing. It's barely readable in the best of circumstances, so there's a lot of temptation to compress code. Er, it's readable, but it's like reading a regular expression. You read it character by character, not line by line.
The other thing APL encourages is writing dimensionality independent code. Just as a good C programmer will write a function to concatenate two strings that works independent of the strings' sizes, a good APL programmer will write a function to accept arrays of arbitrary dimensionality where that can make sense. That's because it was not uncommon to have intermediate results of 3, 4 or 5 dimensions. Also, most of the built-in operators do something useful with higher-dimensioned inputs.
So yes, it becomes second nature, more or less. But at the same time, it restricts the kinds of problems you think about solving with it.
Today I would not recommend APL for any purpose except studying its place in computing history.
