What a terrible proposal. None of these times are sufficient particularly in deep stack tournaments and having to make a big decision and replay the action over multiple streets.  One of the best things about live poker is the luxury it affords thinking players. If players continue to take too much time, the the clock can be called, so if its not broke stop trying to fix it, or we might as well stay at home and play online. I expect this will alienate older players who don't think as quickly as younger ones.