I've never seen anything but simplistic a priori estimates that assume that proteins came together all at once with a defined single sequence. Know of anything that will take me more than 5 minutes to drive a truck through?
What about the likelihood of that next term in the sequence coming together? Certainly the nature of the being that come next into the association is determinative.
In any case, the appeal of Evolution to many people is that it provides them the comfort of a demiurge who does NOT judge them to the discomfort of a God who does.