Why no 20 minutes?

Why isn't there any 20 minute game? 10 minute is too short for me and 30 minute is too long for me. 20 minute is perfect for me. But there is no 20 minute game. And I don't like the 10/15 where you get 15 seconds more or whatever everytime you move because it seems like I get cheated somehow, I get less time than the opponent so I don't know how that work so I just stick to the minute only game but there's no 20 minutes. Why can't they make it or make it that the people can choose how long they want like Majestic Chess used to have.

Play 30 minutes and slow your heart rate.

Just choose time > Custom and write 20.

So far, I used to play for 20 min, but a few of my friends did not have that option, and we thought it might be because I play on the computer and they are on the phone. But from today, I cannot find that option anymore. Did something happen? 

Oh, I found it again, It is not under custom games, but when you click on time you should scroll down to More times to control something like that. I thought it disappeared. 

i also like 20 min , it's best time for me,10 min is too fast ,30 min too long ,i don't need it,i don't want to play under time pressure