Hi
I’ve used mixed in key for years now, I have done loads of mixes with it and yes they sound good.
However I never buy tracks by key, I only ever buy tunes I really like and just use my collection to get through, don’t forget you have the ability to energy boost so you don’t always have to go up or down one notch.
Do you DJ at clubs, do you get booked to play a certain genre? personally I am bored stiff of the genre trap and try to buy variety, again this can help.
Also being a radio DJ as well I don’t have to always mix tunes, I can just play from a beginning and get to play a wider choice.
Ultimately do you own thing and trust your ears, the trap with mixed in key is you can forget how to mix by ear.