Assume that I will put cream/yolk mixture in to a water bath (in a container or a bag) let it there on 80C for an hour. Cool it. This will set. If I agitate this liquid to make it pourable. Will it undisturbed set again? And what will be the level of "firmness" to original first setting. Colloid gels when agitated behave like liquids, left undisturbed do set. Im just avoiding experiment at first, if there are experiences already. Its the basis for use to make creme brule from a big batch custard already set and not being helped with anything added, nor the need of oven setting.
No, it will not set again at all.
The explanation behind it: The custard is not a gel, it is a mixture of proteins, fat globules and other stuff swimming in a liquid (or maybe gel?). You start off with normally folded proteins, which during heating lose their quarternary structure and "hook" each other, thus creating a kind of mesh, filled with the fat emulsion. Once you break that mesh apart by agitation, it will not reform at all, since you cannot refold the proteins.