Yes, you need to use your best judgement. I would spend at least a year at each place depending how good it is. I think changing 4-5 jobs before you turn 30 is good enough, would've looked weirder when you are 40. It should come across as normal during interviews as well. How do you know you are doing what you really want/should be doing if you did not try multiple things? How do you know if a small/mid/large company is your favourite environment? Have a story/plan and have some achievements at each place, always leave on good terms. PS: contractors move around at least once a year on average and it is considered normal (unfair).
I wasn't trying to argue against you, I was just asking for opinions on the limits of changing jobs too much. My own estimate is something like 1-2 years minimum per job.
