A commercial pool should be following the water drain/refill (including backwashing, carry-out, and intentional dilution) rule of ANSI/APSP-11 which for a pool is 7 gallons per bather (presumably per bather-hour though they call it "bathers per day"). If the bather load is high at one bather per 1000 gallons, then this is around 1.2 ppm FC of chlorine demand from bather load in 1000 gallons and would increase salt using bleach or chlorinating liquid by 2.0 ppm. The steady-state salt level accounting for the drain/refill dilution would be (1000/7)*2 = 286 ppm. This number is actually independent of bather load since (500/7)*4 results in the same number. So if you are doing significant water dilution as recommended for commercial/public pools, your salt level won't get very high. In practice, most pool operators dilute less than the recommended amount.
There is additional chlorine demand from breakdown from sunlight which as noted is usually in the 1.5 to 2.5 ppm per day range. That's an increase of 77 to 128 ppm salt per month if there is no water dilution at all. Even with no bather load, there will be dilution from backwashing if you have a sand filter.
As Jason noted, all sources of chlorine will increase the salt level and though bleach or chlorinating liquid will increase salt levels about twice as fast as Trichlor or Dichlor, it's a heck of a lot better to increase the salt level then to have the CYA (or CH if using Cal-Hypo) levels get too high. Using the same 7 gallon per bather dilution recommendation, using Trichlor would get to a steady-state CYA level of 105 ppm which is too high. If using Cal-Hypo, the CH would get to around 120 ppm which is not at all a problem and is why using Cal-Hypo works reasonably when one has such heavy dilution. However, in practice, most pool operators aren't diluting this much, especially when bather loads aren't very high.
Basically, salt levels are pretty innocuous until they get into the multiple thousands (most SWG pools have 3000 ppm salt) while CH can be an issue if much higher than 500 or so (depending on other water parameters) while CYA is a problem certainly above 100 (if not lower, if the FC isn't proportionately raised).
