I learned to transpose while reading the music back in my horn blowing days. I was always in either b or e flat and nobody else was. I play piano in all keys. Now days in my old age, I only play in the key of C and by instinct on the arrangers, and use the transposer, Life is good for old dudes.
Some instruments get to sounding really bad unless you raise the key for them also.
Best to all
Bebop