Most of the time I think it is mostly a failure of perspective.

As an example, I would refer to the myriad of threads about X-Tol.

People seem willing to go through all sorts of contortions to deal with the fact that Kodak recommends discarding X-Tol stock after six months, and many people have difficulty using 5 litres of X-Tol in six months.

X-Tol around here is just under $16.00 for the 5 litre package. If I use it at 1 + 1, I'll be able to develop somewhere between 20 and 40 rolls with that package. If I use X-Tol replenished, I'll be able to develop about 50 rolls from the first package, and about 70 rolls from subsequent packages, if I'm not required to discard it due to lack of use.

If my volumes are too low, and I waste a third of a package, it still means wasting just around $5.00 worth in six months, or $10.00 per year. That is the perspective that is often missed.