Here's one source.
In an interview with Sports Illustrated’s Michael Pina, Kerr said that his mentality with regards to calling timeouts is derived from his former coach, Phil Jackson.
“It’s good for a team to get itself out of a ditch instead of relying on a timeout and grumbling at each other. Let’s communicate, get all five guys [working] together and execute a play. And if they can do that on their own, it’s very empowering.”
https://clutchpoints.com/warriors-news-steve-kerr-subscribes-to-phil-jacksons-philosophy-about-calling-timeouts
Pop is more the opposite.
Spurs head coach Gregg Popovich can be a mystery at times, but one thing is fore sure: in his world, it’s never too early to call a timeout. Spurs fans know just as well as his players that if the opening possession is botched too badly, an angry Pop timeout is coming. In fact, according to ESPN’s Stats & Info group, Pop has called 50 percent more timeouts inside the first two minutes of a game (30) than anyone else since 2009, and some teams have never even called one.
https://www.poundingtherock.com/2018/3/19/17140414/gregg-popovich-and-the-art-of-early-timeouts
There is probably a good middle ground where coach calls a timeout, but doesn't talk to the players during the timeout, lets them hash things out on their own.
