Victoria, has it been in this potting medium and big pot for the whole time your mom has had it? If it has been happy in potting soil for 3 to 5 years I'm with Jim on this. Nothing succeeds like success and you have had a lot of success with that orchid. I am generally a proactive type but sometimes the rules can be broken.
BTW, my son has a phal in potting mix and I know for a fact he over waters but that darn thing never stops blooming. Go figure.
