GPC won more premier league titles than anyone and rotated absolutely regularly , frequently putting donkeys like O'Shea Smith and Kim in for his stars sometimes it backfired but he knew on balance he had to maintain squad sharpness through to the end of the season .In short, squad rotation (weakening your team in a calculated gamble) doesn't work. Play your best team all the time.
On pitches like ploughed fields, Forest won the League over a 42 game season using just 14 players. It was the days of little protection for players.
Squad rotation works and has worked for most premier league champions of the modern era.
When Forest won the title no teams rotated so they were doing the same as everyone else, the distance players run in the course of a match and the intensity the matches are played has increased dramatically since those days.