I can really tell the difference as I age. One of the big factors is experience to some extent. After a while you get a chance to think about the past and you get to repeat jobs where the learning curve was high the first time you did it, after the second, third or more time you get better. One gets to see others, you can copy and improve.
An example, a mechanic that worked for me was doing a remodel and it involved a service upgrade. He has the good fortune of having a nephew that is an electrician, a young fellow journeyman level, maybe 4 yrs or so. He did a decent job, it passed inspections but the design really left some room for improvement where I would have made it more practical and even saved some expense on material as well as made the labor significantly easier and really improved access for the out buildings as well as the garage addition. Nothing really wrong with it but it just could have been done better. An apprenticeship last 5 years but a guy really gets better at 20+, you just get to see so much more to draw from.
My profession is welding/steel fab, I look at the stuff I built 30 yrs ago, now so much lighter and faster, way less material and time. A lot of these guys are so talented or their comprehension is better, they are smarter than I will ever be that they have a big advantage, better training will be a factor. (a couple on this forum come to mind), in short order they will go flying beyond me by leaps especially when things get real complicated and technical. Wiring a house or garage they would have trouble beating up on me but their ability to troubleshoot complex problems will leave me in the dust especially given a bit more time and experience.
I just escaped from Alberta in the spring,you couldn't pay me to go back even just to visit.I shouldn't say that,the job market here is getting pretty tight,I may have to do a stint in Fort Mac if a gig doesn't show up soon.If anyone in the mid island is looking for a versatile electrician I'm available.