[Capricorn]

I find this discussion very interesting. I am also an average book reader with only basic html understanding. Due to all the changes in sigil, the question - as far as I am concerned - boils down to: what is the best way to validate the epub, and catch all mistakes, going forward with this version of sigil?
So far, I check the css with the right-click menu option "validate with W3C". Then I run the gumbo parser (green button). After that, I validate the rest by starting flightcrew plugin, correct mistakes, repeat flightcrew plugin, correct mistakes,....etc. At the end of that, I run epubcheck plugin to be sure nothing is left in terms of mistakes.
So far, that seems to catch most stuff.
Is that how we are supposed to do it or are there better ways as there may be mistakes we do not catch that way?
Of course, the above process still assumes that, when you find a mistake and do not understand it (as an average book reader), you go out on to the forum in order to figure out what the hell went wrong. Which can be time-consuming at first. But I figured out quite a few things that way. And through trial and error.
I suppose this is what has been said in the above posts: if you do not understand it, ask in the forum.
And this forum has been quite amazing. I ask very basic questions and people still try to help me. Utterly brilliant.

Anyway, any and all feedback as to the optimal way of working (to catch mistakes in the epub) would be extremely interesting to me.