–ting measures across lines: where he finds extra horizontal space in a line, he puts a fragment of a measure there, rather than waste that space. Was paper expensive?
And what about all the candles used to illuminate the parts? Not a single drop of tallow or candle wax or darkening due to the close proximity of a candle has been detected or reported regarding Bach’s original parts. Touching the parts while carrying them or turning pages would tend to leave traces, but these are not in evidence. Eventually these copies of the original parts would be collected and deliberately destroyed by Bach so that they could not be used to reconstruct the cantata.And yes, I'm pretty sure Bach saved as much paper as he could. The autograph score to the Christmas Oratorio uses spare staves all over the place. This is not a page-turning consideration. An aria may coexist side-by-side with a chorus for many pages at a time to evidently prevent those 2-3 staves at the bottom of the page from being wasted.