EV Question until all the regions are completed.

[Cordian]

So i was wondering if it will prove useful to start EV training while in Kanto for my Pokemon.(Currently at 5 Badges going for the 6th).
I know and i did my research BUT what i want to know is if there is a point at EV Training for a team of Pokemon i may never use again. For example a Gastly may be used later on even after Kanto E4 but Exeggutor may never be used again later on. Should i invest some time on EV Training for my Gastly or should i pay attention to it later in the game?

Edited September 8, 2024 by Cordian