Tbh, in a remote company, I would call this an "on-site" even if you don't have a home office to go to.

My previous company, we did the fully remote thing pre-pandemic and had a good culture, but I found meeting up once a quarter was really effective.

Reasons why:
1- No one has solved the remote whiteboarding problem. There is nothing quite like a few people sitting around a whiteboard, drawing pictures, looking in the whites of each others eyes to see if they really understand, and debating the tradeoffs. You can simulate this remotely, but its just not nearly as effective in my experience. In general, I found that about once every 3 months we would have a pile of problems and things we are seeing as potential problems on the horizon that we want to brainstorm on how to fix in a way that chat did not facilitate well. In fact, I would send out a list of these items ahead of time so we could deliberate on them and then present ideas. Things like: "We seem to be generating a lot of metrics that cost a lot of money to store and we only use them when debugging thorny problems- how do we try to make these smaller/more useful?"

2- Text communication is great to a point, but sometimes perceived slights can build up, or maybe someone's communication style is just off putting to you, and you start to build up animosity or perceive there to be animosity that just isn't there. Breaking the ice by just talking to the person in person almost always makes that friction go away.

2a- Often you work with someone and may think they are not performing, or not very smart, or an **hole or whatever, and sitting next to them for a day or two makes you empathetic to their situation as you see how many times they are getting pinged by other teams/people. Sometimes sitting next to them makes you realize they really are a problem and you can start focusing on your efforts on routing around that.

3- It lets you get to know people socially. I find that as we move into an ever more surveilled environment, just talking over slack becomes an ever more fraught endeavor. Discussions about the difficulties your kids may be giving you or the fact that you had a little too much fun last weekend are now archived and mineable for more or less forever. It just puts a real damper on making a connection with your team mates. I have a real example of this at the end of this post.

4- Its fun? Getting away roughly once every three months and spending time face to face, in a new city, is generally pretty enjoyable. We would try to do a different region each time so that no one was stuck traveling a far distance all the time- and in the cold winter months, we would try to go to a warmer location, and vice versa. The ability to socialize with coworkers outside of coworkers was always enjoyable for me.

Real example of socializing on work channels gone bad: At a fairly brutal place I worked at during the pandemic, which reluctantly allowed remote work, I was chit chatting with a coworker I was friendly with, and mentioned how I had had to work the previous three weekends, which was really grating on me, and I had pushed back on checking out another change the upcoming weekend because I needed a "Mental health weekend." This got flagged by some system, next thing you know I am getting a call from my boss asking if everything is ok, and he wouldn't admit at the time, but they were actively surveilling our messages and looking for stuff like this amongst other things mostly related to IP theft, insider trading, etc.