They won't get weaker, but yeah, if you tape constantly, the ligaments in your fingers won't develop much strength. I'm rocking two torn ligaments in both of my ring fingers, from shorter randori sessions where I didn't bother to tape, so I have to tape mine (I'm using 1in tape for that). I saw a hand specialist, and she recommended that I do the buddy system, where I taped my ring and middle fingers together, which forces my ligaments to still stretch and keep ROM while they heal.
Otherwise, I only tape them during big open mats (which can last for hours of nonstop randori) or when I compete.
I tape them exactly like Xande does at the start of this video (thank you Zankou for constantly posting this in the judo thread), and it allows me full ROM, but also allows the cross tape to take the load of most of the pressure put on the fingers.
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