First off I will say I don't know the proper etiquette and I guess it depend on what you mean when you say updating.
I sent in my eras with just my step 1 grades. I got my step 2 grade back about 2 weeks later and it was significantly increased from my step 1 so I immediately resent my comlex grades to ERAS. The programs when they were looking through candidates saw there was an update and downloaded my step 2 grade within a week. That has been the case for every program and I diddn't have to contact any program individually.
As for transcripts, I wouldn't bother updating your fourth year transcript for each clerkship as it may become annoying to your deans office and the programs. I might consider updating my transcripts if I got a run of great grades that were not typical for me, and probably will update once closer to match Nov/Dec.
If I notice a program has not downloaded my ERAS documents at all or hasn't downloaded my update on their own, I'd consider emailing them within 2 weeks+ or so just to let them know I'm interested, and I have new material in that may significantly affect their desire to interview me. If they have downloaded all your material and you know a resident or the program director, or have rotated there, but you have not gotten an interview I'd say you are fine emailing the program director or resident and reminding them of your interest. Personally, if I diddn't know anyone at the residency and I had not rotated there, and they had downloaded all my info from ERAS, but not set up an interview yet I would not email them requesting an interview.
This is just what I've decided to do, but I hope it helps.