Ich in tangs

[Baldy]

Hello all.

I have a quick question regarding ich. I know some people say they accept that their tank has ich and some people go through painstaking trouble to prevent it and get rid of it from their DT. If you ensure that your tank is ich free (hypo all new additions, run the display fallow for 8 weeks, etc,) is it still possible for fish to get ich when stressed? if all the trouble is taken to make sure ich never gets into a system, then its inhabitants should never be able to get ich regardless of stress right?