It does at higher levels, but its also vice versa. Ask any 7k player who also plays 4k and they will most likely say it helps. For me, I saw a drastic increase in 4k stamina, LN reading, coordination, and finger control after learning 7k up to my 4k ability(in terms of SR). And as I got faster in 4k, the speed translated over to my 7k as well, making fast patterns feel much less stamina draining. But keep in mind, I started seeing these results at around the high 4* range in both 4k and 7k.
Also, you should keep playing 7k if you find it fun. If you don't, then try 4k and see how it goes as well. I will say, the 7k player base is dying because of the lack of interest in the keymode, which is why I encourage you to try 7k first to see if you like it or not. But once again, it's whatever you find fun. Good luck man o7