I think this would depend on your definition of very often, as well as some other factors such as consumption level, bio level, how you are supplementing ect. Most successful tanks test ALK at least weekly. While some reefers never test period, the majority do. Its easier to realize small deviations in chemistry by testing and correct accordingly than to wait until your testing to figure out what went wrong. Its also cheaper to buy test kits than it is to replace coral. The OP states he is a mechanic, Its easier to check the oil in your engine than it is to ignore it and pay for a new short block.