According to Rhea herself, the original purpose of the reduction gear was to only have a single one and thats it. Also why the animation bugs out when you got 3 or more.
But as it turned out, chaining reduction gears would stack, so using more gears would proportionally increase efficiency. Because the base efficiency was quite bad at the beginning, particuarly combined with steam being ressource hungry, chaining gears basically became the norm, and using 3 gears at once is basically the only way to use medium steam propellers without going bankrupt. Hence monstrosities like this are always needed:
A massive, 2x3x12 chain of reductors. Using less is not viable, probably wont either with foreseeable future efficiency changes, and using more you get just free thrust.
While I thought it to be a challenge at first, at this point those reductors are just annoying to deal with, a chore that is heavility limiting vehicle design using steam props. It doesnt add much, and is part of the reason why steam engines are insanely volume inefficient.
So I'd suggest to go back to the original plan, remove the stacking ability of reductors (not necessarily remove the ability to chain, so it doesnt break blueprints). Then boost the reductor efficiency; after building hundreds of steam ships in different sizes, IMO 3x reductor would be a good baseline to go for the new single reductor mechanic
This is a bug that became part of the game mechanics, but after all I dont think it adds more to the game than it takes away.
