Slack is not a replacement for scheduled meetings though.
> If a conversation takes longer than three minutes to conduct on Slack, in real/video/phone life please. There is an illusion that work is getting done faster on Slack; the opposite is true, work is slower and of poorer quality.
People say meetings are high-bandwidth, but getting a bunch of engineers in a room is very expensive (literally - hundreds of dollars an hour) and you get synchronous, blocking discussion (one person speaks at a time - else, chaos). I am much, much less distracted participating in a "long" slack discussion (which I can check in on every few minutes or so) than I am with all my attention paid to listening to a meeting.
Personally, I find few people on any given team are able to communicate well on the fly in a meeting and I see people (including myself) frequently asking for clarification due to misunderstandings, which contributes to a meeting dragging. Meetings are also _notorious_ for encouraging unfocused and unstructured discussion, unless you have a good moderator or some structured approach to a meeting (like a lean coffee style). A lot of this is improved in a Slack conversation because people are forced to distill their thoughts into text, they are able to reread messages for clarification, and we've had good success using Slack threads for focused discussion of particular topics.
Meetings are also not archived by default, which isolates the people unable to attend the meeting - especially when you have in person meetings that are not remote friendly. Slack discussions are at least discoverable through search. One team I was on started recording meetings and rewatching hour long meeting minutes to get information is actually terrible. Searching through Slack is not perfect, but it's infinitely quicker and I frequently do find what I want.