I just got a bit confused checking some guides. On several places I see it is stated that Resto Druid Mastery: Harmony affects only max of 3 HoTs.
Example Wowhead Mastery: Harmony passive spell: Your healing is increased by 5% for each of your Restoration heal over time effects on the target$witch<1>[][, up to 3].
Example Icy-veins Resto Druid guide: Your Mastery, Mastery: Harmony, increases your healing done to a target for each HoT that you have on that target at the time, up to 3 HoTs. The amount by which your healing is increased depends on how much Mastery you have.
But in-game my Resto Mastery doesn't say anything about "up to 3" and I see on various forums how people talk about 5-6-X HoTs stack for max mastery value.
What's up with that?!