We know hreflang is pretty complex and in many cases, you don't necessarily need it but if you do it right, it can be great for Google in understanding your multilingual and multiregional web site.
But what is better to do? Is it better to try to do hreflang correctly and then get it wrong (by accident) or do no hreflang at all, so you don't have a shot of getting it wrong?
John Mueller of Google responded to that question on Reddit and he said it depends on how you do it wrong.
If you just mess up the syntax, then it is like Google doesn't see the hreflang at all and it is the same thing as not doing hreflang. So if some of the pages do it correctly and some don't, in that fashion, then it is probably best to do it wrong some of the time.
But if the hreflang is between the wrong pages then it is probably best not to implement it at all. Like you tell Google the English page A page is really a Spanish page A page but it is not.
Here is how John answered it:
If hreflang isn't valid (non-indexed pages linked, invalid language codes) then it's ignored & the same as not having it at all (this is on a per-hreflang-link basis, so if some are ok, they'll work). If the hreflang is between the wrong pages (eg the English "Fish" page is connected to the Spanish "Chicken" page), then that would probably be worse than not having hreflang set up at all.
Forum discussion at Reddit.
