I was recently in touch with the European support department about this. They did suggest emptying resin out to extend lifetime of a tank, but could not guarantee it. So this kind of raises the question of what happens if we follow the advice, and the tank leaks on week 11 (when using Engineering resins or Tough, for example).
As a hobbyist who does not run a business or company, having to replace a tank after only maybe having time/funds to print 1 cartridge becomes very expensive in the long run, and may turn out to not be a viable option.