Is a tarp better than a rainfly?

Colleagues,

In preparing for last week’s hike, I had a great idea. I decided to replace our tent’s rainfly with a 10x10 tarp. A rainfly hugs the shell of the tent, essentially creating a second skin. 
 
So why did I want to replace the rainfly with a tarp? The tarp is more flexible and can be set up in different ways. I also thought the tarp would protect a larger area from the rain under which we could cook and relax.
 
I was wrong. 
 
Not only did we have less room, but the configuration of the tarp allowed lots of water to splash onto (and into) the tent, so everything got damp. This was a big deal as temperatures were expected to drop, and wet gear loses insulation power and is heavier to carry.
 
The frustrating thing is that I could have tried the set up while we were still at home. The pain could have been avoided by a low-risk implementation of my great idea.
 
Next time I have a “great” idea, I need to test it out in a low-stakes way to make sure it really is great.
 
What about you?
 
Do good and be well,
 
Frederick