I don‘t understand. This idea has been put forward and shot down with very valid criticism and experience from other games for years.
Why not try the likely more feasible idea where only planning phase has a clock, and each player gets around 30-40min total? The best number could be identified and adjusted.
The point is that the worst occurence of slow play is during planning, and this version already fixes that while it can‘t be exploited as easily as others ideas. Others likethe one put forward by FFG.