According to the 50-year mission volume 2, Gene was still very much involved in season 3 and still gave some notes in season 4 but came in less. By comparison, he was arguably about as involved with S4 TNG than he was with S3 TOS. However, Berman and Piller were able to handle him more, and when he said no to a story, they could often change his mind. Examples are developing Worf and the Klingons in general, any time travel, and any serialization. Leaving Worf disgraced after Sins of the Father was a turning point. A door was left open almost by mistake. By the end of season 4 he was about gone. He died soon after a personal screening of ST6. Apparently he was not coherent enough to really watch it.
By now, the torch was passed to Berman, or as Marina Sirtis was quoted, Berman didn't so much have to torch passed to him as he pried it from Gene's still warm hand. Harsh.