In the early days of WoW, maintenance every Tuesday was at least 8 hours. Every week, no exceptions.
Everyone gettin’ all excited for prepatch, don’t. It will be announced at least 2 weeks in advance. They’ll say it’s an 8 hour maintenance, servers may be stable enough so everyone can start playing Thursday with some lucky ducks having a mod-free Wednesday session.
No prepatch. We will get a 2 week warning for pvp season, mythic season, visions, AOTC, etc to get finished up before they drop their new album of the year.
Considering Tuesday maintenance used to be a minimum of 12 hours every week in the early years of the game, skyrocketing up to 18+ hours at times, I think four hours is fairly modest.