"manageable length" is a correct and usable phrase in written English.
It can be used to describe a sentence that is not too long or complex, and is easy for the reader to understand. Example: The author's writing style is clear and concise, with each sentence written at a manageable length.
Just at a more manageable length for the under-11s.
Negotiators have whittled down the text of the proposed agreement to a manageable length.
You want sheets 10cm wide and a manageable length so cut them if necessary.
But the Rimini Protokoll directors have kept their version to the more manageable length of one evening.
It keeps classes small and of manageable length (two hours, with a break in between), with lots of repetition and hands-on practice.
The next afternoon, just after the lunch break, I nipped into the rehearsal room ahead of the director and dictated to the cast a series of cuts and transpositions which reduced the text to what I considered manageable length.
I assured him that these days we tried to keep things at more manageable lengths — perhaps five thousand words, or so.
It's my favourite of their albums: all the signature numbers in one place, at manageable lengths.
Boil 1 minute, then drain, rinse briefly with cold water, and using a scissors, cut into manageable lengths.
Dry the octopus pieces using kitchen paper (don't worry if some of the skin begins to rub away) and cut them into manageable lengths that will easily fit on your griddle pan.
With a fluted pasta wheel cutter that he had carried back from Italy, he cut the dough in manageable lengths, then dabbed on mounds of ricotta filling, folding the dough over and sealing it meticulously, pressing out each air bubble with his fingers.
