Yeah, it's a bit soon for the guest reaction to be anything, nevermind great.
If you're talking about comments post-ride to the staff, you're obviously not getting the full picture.
And an actual study would need a decent sample size - unless they've been drilling it hourly with people with iPads it's unlikely you'd have the sample size the industry considers the minimum.
I don't know Uni's methodology... but an immediate post ride survey primarily serves the purpose of informing ops of what is going wrong in their operation. It's not getting the bigger picture guest opinion because people don't know the ride is open, opt out, are denied because of ride requirements, missed it due to downtimes, etc...
It'd be like a post ride sample from Test Track in the early years that everyone loved the ride with no mention of serious issues with downtimes. Well, the people who got to ride enjoy it - but that's obviously not the whole story.
So time becomes an element - how long after is it even remembered. Does it drive people to the park. Does it extend their day or does it replace another option. How does it relate to their overall ratings.
Very little of that could be captures and analyzed in such a short period of time.