I played on the test server today and noticed the same. The timer got to 5 min 10 sec after 12 wins and didn't increase any more after that. This brings the minimum total maximum waiting time when the 20th match finally starts running down to 1 h 17 min 20 sec.
It is a lot of waiting, especially when I play at times there is no1 in top 20 so I have no chances for human opponent anyway. Means the closer I'm to purple chest the bigger waiting punishment I get.