Lore-wise, how much training do engineers need?

The Omega interrupt has Shepard say they're not a stupid grunt, suggesting that being an engineer is about intelligence or at least education (as opposed to just a different setting on your AI assistant in Andromeda). Likewise, the dedicated engineers in the party are all people with a strong background in technology.

Of course a real engineer needs plenty of education, but Mass Effect's engineers use omni-tools and shoot ice beams, so clearly it's not a 1-1 resemblance (just as a relative layperson could create Mass Effect mods while early computers took intellectual elites just to run). Also, you can switch classes between games, and there's only a few months between 2 and 3.

So I'm curious how much Shep being able to retrain as an engineer is "canon" vs. just a nice quality-of-life feature. They do seem to have a pretty robust education, so perhaps they have more of a foundation than most even if they're not a dedicated Engineer Unit.

Is there any lore that suggests what it actually takes to be an engineer?