Greetings. I seek your input on this. For years, we keyboard players have been told, "now go learn that song in all 12 keys. What if you're in a small-group setting with a vocalist, and she says, "How High The Moon, but in D-flat?"

Well, in the modern world I can simply press a couple of buttons on my keyboard and play in what seems to me to be G (where I learned that particular number) but which sounds like D-flat, right? I get that this doesn't work on a grand piano, nor on, say, sax, but for regular keyboard, isn't it better for me to be perfecting the songs I know in the keys in which I know them, than to be practicing "Blues in F-sharp" or "A Foggy Day in E"?

Other sources say, well, learning those classic songs in unfamiliar keys will help your fingers, help your ear, that sort of thing. But my question is, is that the right use of my practice time?

What are your thoughts?
Thanks,
A Guy Who Isn't Very Good