Yes, it would be correct to say that “once you finish the game in the post game if you already have all the materials you need it takes 10 minutes just to roll the enchantments”,
and even then it is assumed that you heve a blue item where you want a blue item and a purple item where you want a purple item and that you are not unlucky with the rerolls, if not it can take you even more than 30 minutes (assuming you have all the materials ready and that you don’t run out of embers).
And in fact in “The RNG Problem, Enchantment System Vs Gem System (Refined)” I also complain about this unnecessarily tedious part of the process (when you have already obtained all the materials you need) which essentially takes away the joy of making a build.
If we add to this the double RNG element of finding embers in random quantities and burning a random amount of embers to Reroll, it becomes clear that making a Build in NRFTW is not a pleasant experience.
In this other post there was a discussion about What should be the appropriate difficulty of making a “perfect build” and this is my opinion: