Err, no, it's actually really easy. Just give them a choice in the matter first. You do realize you're arguing for toying with people's futures based merely on effectively unproven methods because you just feel like doing it? Futures that have inherent value because the
people being toyed with are inherently valuable too. But no, it's totally fine to not be held accountable for your actions. I mean, what's the real damage done here? Think about how expensive it'd be, or, or, how long it'd take if not! That surely justifies just going to town on people, right? :/
That's essentially what you're arguing. Perhaps not what you intended, but it is what it becomes given the context, and more importantly, the people involved that you disregard so callously.
If it's so darned expensive to do, have you considered that you have the free will and intellectual sophistication required to just . . . not do it? If it'd be so expensive to recuperate a group of people, either your methods have too high a probability of requiring it or your method is just perhaps not ready yet if the potential end result are that disastrously bad. Either way, it points towards going back to the drawing board instead of to town.
But if it's oh so difficult to get these studies done, you know what you can do? You can do it over longer periods of time, just like you bemoan, because that larger time scale will stop you from ruining other people for your own curiosity of will x work in y. You could give people the choice to join the study, you could have smaller cohorts every time and refine the process as you go, you could keep each cohort limited to a year or two to avoid long-term damage, and you could test in different age ranges to get more data.
The list goes on and on and on. Almost like studies on people require larger caution than just testing to see what works without any precautions and going from there. When learning about the scientific method, the idea that people are, you know, people and not test subjects is pushed constantly. Because certain people sadly need that reinforced to avoid being callous researchers. It's oh so easy to forget the numbers you toy with are real lives with real value regardless of what is done with those lives.
We trade immediate results and dubiously better efficiency for larger time spans exactly so that we can ensure the people in them remain protected. Giving people choice in the matter, and letting guardians weigh the value proposition (like other studies have done successfully) by giving them the prerequisite information required to make those decisions, allows for a higher likelyhood of avoiding disasterous effects on those very same people. It's not "generational inconvenience" when lives are affected for multitudes of years; it's callous impatience. It's not "no change ever," is respect for the people involved in attempting those changes and respect for the potential ramifications of those changes. It's borderline evil to disregard people because you, and I do mean you here, don't have the patience to ensure people's safety because, oh no, it'll take a while, or cost a lot if you're held accountable.
Rather, it's okay that things take time, it's wanted that we don't make haste. Because haste makes waste. Because we don't need immediate results. Because we're not working with machines, we're working with the single most valuable thing we have on this earth; a human life. Have some compassion for those people, and you'll find that change doesn't take so long after all.