It's funny because this is something that just never came up for us! Probably because we're old but it was just a given that the day we had our wedding was the day we got married legally, and when it was too complicated in Mexico (namely because of divorce dates) we switched to looking for somewhere that it wasn't so complicated and Jamaica was it. It was super easy and the marriage certificate we have is absolutely beautiful! lol
My stepson married a girl from the US. She had to apply for a fiancé visa for him, and when it came through and he moved to the states, they had 90 days to get married. We just thought they would have a wedding and have family there and get married. But they actually got married by a justice of the peace 5 days after he moved which was March but then they didn't do a wedding until the beginning of October. We had a hard time with that and really didn't understand why they didn't just get married when he moved. I have to admit, as an old lady I still don't understand the wedding before then the other wedding but I do know about the requirements for Mexico, which can be a bit daunting.
I guess in the end all that matters is that you've married the love of your life!