Google then changed the period to 15 minutes which is far too short. Many games start off with large downloads that won't have finished in that time. I'm currently looking for a podcasting app and there is no way you can evaluate one within that time (little details matter).
Some try to solve this problem by having separate free versions that have less functionality, or various complex schemes involving paid unlocks, but neither solution is perfect.
It might help for expensive software but for something that is a few dollars I'd see it as a negative as a developer.
For example with a business app like Grafio, I want to test drive it to see if it works for me. Then I can pay a significant price for the app - if I am using it in a business setting my time is worth hundreds of dollars per hour and the prices of apps are not really a significant expense. I would want development of Grafio to extend further towards supporting my business needs, which is Visio import/export, and I would gladly pay for that feature.
I dislike when the free app is missing important functionality (this defeats the test drive aspect) and I dislike when the in-app is a subscription. I find it obnoxious when apps have too many in-app purchases. It becomes an annoyance to have to pay $1 to read, $1 to write, $1 to save. Just ask $3 for "full functionality" from the start. Don't be silly.
I like when the app is fully functional and I can choose to pay different amounts to support further development.