IMHO yes, because if they don't pay attention to such things, they're going to make even more subtle mistakes in the future.

Besides the explicit mention to "see NOTES", the fact that most of the format specifiers are mnemonic for the common parts, like H M and S for Hour, Minute, and Second, should be enough to arouse some suspicion when you see G being used for "Year". They weren't assigned arbitrarily --- with the most mnemonic ones being assigned first --- and presumably, people wanted to print years very early in its history, so your next thought should be "then what did they use Y or y for?" If you're really observant, noticing that months and days are lowercase, you may also ask "what's g?" That will naturally lead you to the right choice.

My point is, there's a pattern to these things, and the instinct to ask "why?" and find out when something doesn't feel "right" is very important. More abstractly, "reading requires thinking".