Board Thread:Questions and Answers/@comment-194.254.125.132-20151101185708/@comment-24436495-20160902185530

And one more fact about time in the tower:

In one of siu's blog post he stated that the 6 years time skip was equal to 2-1 years in real life, so basically 1 year in the tower is like 4~2 month for us.

And still, 600 years in the tower is a lot even in real life perspective.