How much time he saves who does not look to see what his neighbor says or does or thinks.

Monitoring other people is expensive and never shows up on the ledger. The comparing, the checking, the small adjustments to what they might be thinking take real hours and real attention and return almost nothing. What is left when you stop is not only time; it is the quiet you need to know what you want independently of what is being displayed around you.

Try it in one specific place, since giving it up wholesale is unrealistic. Cut the checking somewhere easy to measure, and watch where that attention goes instead. Most people find they were not short of time so much as short of it uninterrupted.