60-70% seems nuts to me. 10%-20% feels about right to me. That's a day every week or two. Builds cohesion and lets you do some effective brainstorming sessions, and then the rest of the time you do actual work far more efficiently. I mean you do you, but I thought I was suffering from lack of office time, but that's way too far in the other direction for me.
It's been 5 years and 3 jobs since I've been to an office. My last job I honestly don't even know what state my job was based out of. That's a little too disconnected. But just a little.