OCR4 does not work any time during the combat phase; only when you spend focus
Given that it actively hinders focus acquisition through stress generation and/or forcing a less flexible, more easily blocked dial, it's really not a great card by any means
Attaching what is probably among the worst by far epts in the game to it does not IMO help matters
Overcharged does not hinder focus acquisition for the same reason Corran's ability does not prevent you from firing.
Assuming you go white green white green with overcharged TLT Y's, you haven't actually lost any actions. Over the course of the game you're still getting the same amount of actions if not more with Overcharged.
If you're alternating greens and whites you're only using the ability every other turn. And your opponent knows exactly where you're going next round on the turns after you do use it.