IMO, if it's not leaking it's 'good to go' ... BUT ... Every time you empty and move and refill a tank, you're changing the pressure on the seams/joints, and there's a possibly of a new leak.
If you want a tank of water in your house, you need to be aware of that fact.
I agree with you on one level, but on another level I do not agree with you...
There is no time limit on 'water testing' a tank. No matter what, a tank can pop a leak at anytime for a myriad of reasons. The only insurance that a tank will not leak 10 seconds from now, is to not put water in it. That is the fact that all hobbyists need to be aware of.
The only thing you are left with, is mitigating the cost of the potentially catastrophic damage caused by a tank failure. For renters that means catastrophic renter's liability insurance; for homeowners, it means an added aquarium clause to their homeowner's policy (in most cases and higher premiums) to cover catastrophic flood damage due to aquarium failure. Both also should include aquarium related fire damage (misuse of electrical equipment.)
For a tank builder, that means catastrophic liability insurance, and $250,000 worth, does not begin to scratch the surface.
As far as 'at home' related hobbies go, about the only one that is 'more risky' is chemistry, (read making explosives,) in terms of potential damage costs.
The reality is the risks are rather low, but none-the-less present. You do have to be prepared, however, just in case.
