not just that...

I recently spent substantial amount of time with people face-to-face who spents 10 hours/day every day on Splinterlands.

About 50% of it is gameplay, but the other 50% (and this is the important part) of time pure studying the game on pencil and paper and spreadsheet. They have mentally memorized ideal 6 card builts on every ruleset with every possible mana cap, and can improvise on the fly.

These people can challenge you, given the deck, you can't beat them. Period. And I tried, not that I am very good, and I couldn't :)