Sigh... (hopefully recapturing everything)

Most of this is from Chad Millman's pocast with a bookmaker that I don't remember and don't feel like looking up. I stopped listening because there was a super annoying baseball ad that was 2-3x louder than the pod, but I digress.

You are mostly correct, one factor you did not mention is the changing max bet.

For big games, say NFL, they have a meeting where they discuss the potential lines and reach some consensus. This opening line is usually aimed at equal betting on both sides. When the line opens it is all pro bettors waiting to pounce, with a max bet of $1-5k or something. Some of the pros are known and trusted by the odds setters. If the pros are all on one side the house will adjust the line (or the vig if close to a key number, e.g. 3, 7). After this early adjustment the max bet goes up to $10k+.

With popular aka public teams sometimes they open with an adjustment off the "perfect" number knowing they will get money on one side regardless of the line (i.e. GB, NE). In these cases they will take uneven action thinking/knowing/hoping they have the right side.

In smaller markets (West Coast Conference, NCAA bball) the house does not have enough info so some pros will focus on these games. The pro can take advantage of in-efficient lines and there is not public action to necessarily offset for the casino.