OP, have you had a recent visit from a maintenance engineer from a certain German brand of machine?
We had one recently and he advocated the 90 degree maintenance cycles once a month, and then went into sales patter about the own-brand descaler.
I thought the whole thing was a sales trick, but then he dropped the patter and said straight-up "look, selling this stuff isn't my job, but Limescale really does kill machines and it's worth using Calgon or something like it".