This is also one thing I love about sous vide cooking. It’s slow in terms of total time elapsed but usually very efficient in terms of time spent actively cooking.
There's a decent caled a "pot watcher" (aka: boiling-rattler) that is a mechanical "hey, it's boiling" indicator.
Anytime I'm cooking or thinking of cooking, I'll always throw water into the tea kettle (countertop boiler) and start it off, for exactly the reasons stated.
I'm very thumbs up (and already follow) almost all of his advice, including the "use two boiling elements to get water boiling faster".
How much time when cooking do you spend waiting for water to boil when not doing something else? For me it’s zero. And if for some reason it wasn’t zero that means I’m cooking leisurely and don’t much care about time.
I definitely don't sit around doing nothing when I'm waiting for water to boil, but very often the water is still on the critical path (e.g., because I want the pasta to be done ASAP even if other things aren't done yet, or because it's on the critical path even if I can use all that time efficiently).