When I was teaching Plumbing, I had several mock-ups of bathrooms, kitchens, etc. which I would assign to a crew and tell them what fixtures I wanted used on it.
Invariably, they would make a mistake here and there. Some I would let go until they found out for themselves it wouldn't work; others I would have them to change on the spot, depending on the 'teachable' moment.
I never ridiculed them for mistakes; I just told them "its much better to make a mistake here than in a customer's home. Here it is just between us and will be a lesson well learned and when you go into a customer's home you won't make it again".
When we do work for ourselves it may not go just right the first time but we can change our own work and just not mention it to anyone. It costs a little more but its still less costly than having a professional to do the whole thing. If they make a mistake, they tear it out wrecklesly, we can salvage most of our materials and start again.
Let's just mark this one up to hard earned experience and not mention it to anyone, OK?