Not very good idea. Constant salt means the aro needs to use more caloric energy. And like Bderick said, if a fish gets used to a medicine, it will be less effective when you actually need to use it to heal cuts or injuries.
hmmm so i guess the 10 years i have been using it it has been bad? i use it. my fish don't get sick. and my dempsey rammed her head into some slate 2 days ago and you cant even tell. hmmmmmm.
Well, just make sure you dont run out of salt if you're planning to keep going with your routine. If you run out and you do a large water change, the salinity level's going to change and most likely shock your fish to death.
What it died? That fast over night....Maybe stressed? Or something in the water, water company have some bad water come though and it affected the most vunerable?