Certainly I won't be washing my bike that often ..... I was given frame bag and other bits to go on it for Xmas and wanted to put some High Viz Tape strips on it and knew they'd take to a clean surface much better.
In the end I compared the cost per ltre of the Fairy Power Spray to Muc Off Bike Cleaner and the Muc Off worked out quite a bit cheaper so went out and got some along with some degreaser and just a cheaper wet lube for now.
Must admit it's done a cracking job although I think the sprayer that comes with it is designed to use an awful lot of the liquid so you go through it quickly, I'll pick up a cheap sprayer next time I'm in town with a finer spray as their's is a thin jet so you don't cover much of an area and have to keep pumping.
Virtually all of the videos I watched whilst the majority said about lubing the chain virtually none of them mentioned anything about the derailleur ... I'm guessing I just put oil on every bit of those that moves????