BLM: What is the proper use of thunder?

[Malevicton]

Apply thunder2, use thunder3 with the proc. Unlike bio, none of the thunders stack. A more powerful version of thunder will overwrite another, and a weaker version will have no effect (technically still does its upfront dmg, but what's the point).

[MBTL90]

Also, all three thunders have the same dot potency. The difference between 1-3 is the initial hit and the length of the dot.