I quarantine for 2 weeks nerite snails... but I keep it simple. I have a 10 gallon tank that I put a large piece of liverock from my main tank in, and dump the snails and water from the beach in, then leave an airstone on it for 2 weeks, feeding daily. I havent had any problems. I've done the same with hermits.
I used to do the same with algae to feed my fish (including that green leafy stuff), but I've heard of parasitic problems. I used to do this with my 265 and didn't have a problem. But after many years I was forced to shut it down (recession). When I did, I found a LARGE rock crab in the sump! That thing was about 2 inches round and I never saw it until the end.... what if it was in the main tank! I think my wrasses kept the main tank clean. I would go a month to be on the safe side with plants, large empty shells, etc. and even then pick it apart to be safe. You might even try feeding the tank with the plants in it to see what grows. Most fish parasites will die without a host, and crabs etc, can be picked out when they are grown.