There is not a good one size fits all answer. Only sit rules I know about for sure is the within WCHA one, and any move to or within the CIS. (The CIS one is actuallychanging next season, at which point you can move from the NCAA to the CIS without sitting a year.).
There are other factors, like the departing school having to sign off (Witness the player that went from UVM to Cornell a few years ago and had to sit a year). If there is a rule in HE, it is relatively new. Pretty sure it did not exist 4 or 5 years ago, but there was talk at the time of bringing it in. Not sure if the HE "sits" from the past where due to the rule, or the lack of sign-off from the various schools.
To the best of my knowledge there is no ECAC sit rule, but also know that there are a myriad of Ivy rules over and above the ECAC/NCAA rules (red shirting for example).
If you are even thinking making a move, your best course of action is to check with the current schools compliance officer. They will be able to tell you A: what the rules are, and B: if the current school would support the move, as they have to sign off on it, before you can even entertain a conversation with another school.