I'm wondering whether playing in a logged out session to practice each game and then login and play when you have enough knowledge of each game, can this be considered cheating?
The purpose, for example, could be to have better statistics...
What you think about it?

I think it's most probably a philosophical question...

The stats are based on your best time / best moves. You can have a horrible game, which will reflect badly on your stats - returning to the game and beating your previous moves / time will give you better stats.

Thanks for the explanation Adam. I am not anymore caring in making horrible games... I just play as it goes, trying to better myself more and more...

I just did that today, I played one time and then I tried for the second time and did way better. I kind of felt bad because I thought I was cheating, but now that Adam explain it I don't think I'm cheating. Thanks Adam!