Learn from my expensive mistake. I used to swear by hand rollers too, until I had to redo an entire kitchen backsplash on my own dime. That heavy roller feels like overkill right up until it saves your butt.
My uncle did his whole bathroom with just a hand roller. Looked great for about a month, then you could hear the hollow spots when you tapped the tiles. He ended up having to rip half of them out and start over. The extra five minutes with the heavy roller would've saved him a weekend.
I used to skip the weighted roller on small jobs, but then I had tiles popping off after a week. The hand roller just doesn't get enough pressure into the adhesive, especially on uneven walls. Now I use the heavy roller even for quick fixes, and nothing's come loose since.