Watching Rafa today he still goes through his ritual before every serve. Are players being timed from the minute they start their ritual or just when they start to bounce the ball.
I think it's supposed to be as soon as the previous point is finished. There is a little confusion as to exactly when that is, because you could say it's when the ball goes out of play, but I think it's officially when the umpire calls the score. So if there is a challenge, that slows things down, and it looks like some challenges are just an excuse for a breather.
Some of the tv companies are timing the gaps, and there was the issue in Miami where a time violation was given, but the commentators had timed it as being just 22 seconds. These things need to be resolved.
I don't see any benefit in skipping the on court warm-up. I think that's important for the organisers and tv companies, not just the players. Between matches, the crowd will nip to the toilet and for a drink etc, so they need something to encourage people to get back into the stadium in advance of the actual start.