IMO, the older a tank gets....the more stable they get and can almost become “bulletproof” if certain things are kept in check. The same goes for Acropora corals. The reason why most people have issues is because they start with dry rock and throw the hardest acro’s in before 6 months. Not to mention the wild caught are much more sensitive.
Running a tank with PO4 at 2 is just ignorant. NO3 at 150 is even more stupid. I’d personally never let PO4 ever get above 0.2 at the absolute highest and NO3 above 50 at the absolute highest.
Although I like to keep PO4 anywhere below 0.1 and NO3 under 20. Personally I shoot for 0.05-0.09 and 2-5 with NO3.