In your experience with the chain, why do you think she tagged them several times a day? Are they quite pushy with guests to promote them, or do you think she got got something out of them for it?
Same as Sandals / Excellence etc, they like you to tag them if you're doing something on SM, sure. But they don't pester you to do it. Which is lucky as I don't post on SM so they would be disappointed!
They ask you to review on Trip Advisor too but again, not pushy.
I don't think the tagging on every post is any different than any other social media person these days, to be honest. Whether that's your neighbour who is a wannabee influencer or a full-time influencer. Every post has tags on because that's just 'what you do'.
There is probably a bit of her hoping that they'll see her tags and offer her some extras or freebies, but I think it's just the way of the Instagram world these days ie. tag everyone and everything and wait and see what you get back!
I genuinely don't believe the holiday was a freebie. Or even subsidised slightly by the resort. She got nothing 'extra' than anyone else gets that goes to their resorts and the price she quoted was about right.
If they were giving out freebies for SM influencers, they'd want a lot more than she put out there and they'd have given HER a lot more than what she showed.
The service is like that for all the guests. They are known for excellent service standards.