The bane of my productions is that I always feel they can be better.
Analysis paralysis, or never let perfection get in the way of a good piece of work. I don't think any serious musician or production engineer has ever got to the point where they think the work cannot be made any better. However life is short and there is much to be done.
zero in on small things that I have become completely used to from repeated listenings.
I mostly work on between 3 and 10 different pieces of music concurrently over a period of months, this way I don't become too obsessed with perfecting any one of them, they kind of organically grow themselves over a period of time. Some pieces I revisit only years later - (According to my journal, the guitar rhythm for Marrakesh was conceived in May 1978, I put the bass and lead in this year, if all goes well I will finish it by March 2020 ?)
I find having others critique them is a great way to make me hear things with a different perspective
Take criticism from where it comes - it depends who you want to be appreciated and respected by, other musicians? audiophiles? marketing maniacs? or ordinary people?
Looking at the waveform, they are 3-4dB louder
The ravages of age - After surviving a screeching toddler, a psychotic yipping Border Colley, 15 Budgies, playing in rock bands, and growing a bit older, my hearing is not as reliable as used to be. Isn't computer software great, it now shows us what we should be hearing- Beethoven would have been good for another 50 years.