Definitely agree with this. At my initial visit with pretty much all new patients that are not just one-and-done consults (and especially for active oncology patients), we go over expectations for our clinic, response times, what the after hours advice line does, etc.
ALL messages from our patients go to my staff first to screen / triage - I never see things like straightforward scheduling questions, clarifications on where to go for labs, or requests for paperwork; if something is needed (like my signature on something), my staff is trained to do the initial work first.
The other benefit of this setup is that if I clear my inbox at the end of the day on Friday, my patient messages box will stay empty until Monday morning, since my office staff are only checking their inbox during business hours. So even if I do log in on Sunday night to look something up / prep something for Monday, I don't get stressed / distracted by a bunch of inbox patient messages
We also make this very clear when they establish care with us, and I have yet to hear anybody complain that this is unreasonable