Let's assume we are in a COVID-free environment.
In France, depending on where you are, we give different amounts of "bises" (kisses on the cheek) in greeting.
For example, we give two in Lyon, but three in Montpellier and only one in Brittany.
See this map for reference:
Given that, if someone from Montpellier comes to visit someone in Lyon, how many times should they kiss?
And what if these people from Montpellier and Lyon meet in Nantes (where people give 4 kisses)? How many times should they kiss then? What does the etiquette say?
I previously wrote a similar question but it was about "when should one do 'la bise'" and not "how many times should I do it".
What I usually do
So far, I have only ever been in a situation where people give two kisses or more, I haven't encountered any situations where people would only give 1 kiss. I was raised somewhere where we give two kisses, so that's my "default" mode. When meeting with people giving more than two kisses I usually only do two of them leading to awkwardness and possibly rudeness on my part.
Sometimes someone will say "it's three where I come from" and then present their cheek. In which case, I will do the three kisses because that seems to be what is expected.