I think that becomes a thing of the past (or at least should) with the new rookie cap. If I spent $50M on something, I'd sure have a much tougher time writing it off if things look bleak too. Now, you can draft whoever the hell you want and cut bait whenever you want. Other teams may do the same, so maybe you'll take their garbage and turn it into gold (we're the Jets so I don't really mean that). But I think with less monetary investment comes less time and effort investment as well. Obviously you don't want to say you blew a first round pick and you want him to succeed. Plus you'll probably have him under a cheap contract for 4-5 years anyway. To me, that says I've got 4-5 years to see if my high end 1st round pick QB has a chance to become something special. If after 2 years, things still look shitty, then nothing says I can't just draft another one.
When a QB is as clear a disaster as Manuel, sure, but when a QB is just decent enough that you think he may continue to grow it becomes a much different decision.
They can ride the pine and learn. They're all under cheap contracts. It's the NFL, so if you can't take a benching, you don't belong. That should be the wake up call that they need to improve.