There's a lot of speculation, guesstimating and conjecture but I would like to see the figures when it comes to the argument between "fix it when it's broken" and "preventative maintenance". Looking at the total cost of repairs to Toddbrook, Middlewich, Aire & Calder, regular breaches, failed locks etc. Throw in the cost of signs, Facebook managers, media men bean counters and that amounts to a lot of £millions. The cost of employing and training lengthsmen will also amount to many millions but would be good to see a comparison.
As I see it CaRT are supposed primarily to be a navigation authority, but keeping the system open seems to be at the bottom of the list. Unless you are a boater or live near a canal or reservoir that's about to breach, it could be said CaRT have been very successful at everything bar keeping the system open for navigation.