JJ, what's been said here is great..
Personally, i was in 1 of the categories that Berbie mentioned--I just hated the frustration of not sitting in a piano & playing that particualr song I felt like playing as I heard it on the CD or anywhere..so inasmuch as I'm rarely exposed to a piano & I ave transpose button at my disposal--I knew that so much as the transpose button was cool because I could soun good at it's command, I didn't feel I was complete in my playing.
This was all last year.
But because some people here were not just thrashing the tool, but rather encouraging people to learn all their keys, I took that as a motivation.
I used the resources.
I wasn't in a hurry to please any1 but myself (because no 1 is going to applaud you & say wow, you play in all the keys etc
).
So 1st, know why you do it.
I'm glad I took the journey..Now I can just watch some1 play & sort of figure out what they are doing, regardless of key they are in. because I UNDERSTAND the relation of note intervals on the piano.
Now learning all the keys doesn't mean learning all of them in 1 go..you can learn a new key every periodical cycle.
However, some resources here are excellent to help you play in all the keys more or less at the same time..
That was the case with me..
I did the exercises...woke up one day..& realized that I could play a few songs in baby style in all the keys