Yes and No. For me working in a startup having focus time is not available everytime. Times, when there are too many things happening that need your attention, kill your focus time. What I generally do is take some time out in the morning which helps me to tackle these scenarios.
At my old agency job, definitely not. There was a ping/interruption about every 5-10 minutes making deep work impossible to do.
I tried blocking off time to do deep work, and I found that to be the only thing that kind of helped. Not really a tool per say, just something I'd book in my own calendar or tell co-workers in advance.
Absolutely. Time blocking protected focused time (and then turning all my notifications off) works best for me. I use Morgen to do it... slightly biased!
Airport mode + a nice message saying you'll have time later,
if you let people drive YOUR time, you're offering your attention to fulfill THEIR targets, not yours ;)