Using a manual camera to reduce the average rate you go through rolls seems to be a variation of shooting less film. Instead of exposing, for example, one frame a day, you expose one frame every two days thereby using less film.
There’s an initial cost (you’ll need chemicals, a film tank, and a few more tools) and ongoing expenses (you’ll need chemicals). Plus, the cost of storing the additional equipment and disposing of those chemicals.
I scan my negatives at home but I admit a quality scanner is expensive and scanning takes a lot of time.
Khürt Williams Jan 17, ‘23