◆think about a fast worker by hourly

My boss and colleagues often say to me, “you’re fast at work:)”.
I know I’m praised but I feel complicated because it’s an hourly wage system.
Thinking normally, the more I work, the less salary per time is. In truth, I lose motivation.
I wonder why most Japanese companies adopt an hourly wage system?

These days, I think an hourly wage system doesn’t suit me. I’d like to work by volume system once.

Thank you:0