For prints, when I do the standing bath wash, I usually do about seven changes of water in progressively longer baths, like 1', 3', 5', 5', 10', 10', 15', depending on what exactly I'm doing. I might do less than that when I'm washing fixed prints and use Permawash. For pre-washing albumen prints before toning (the sequence is print out under UV/sunlight, prewash, tone, rinse, two-bath fix, wash), I wash until there is no more milky silver precipitate coming off the prints.
I've started doing silver reclamation with my fixer, using the simple steel wool method. I don't know what I'll do with the sludge yet, but I figure I can accumulate it for several years before I have to decide, and meanwhile, I won't be putting as much silver into the waste water.