[sulam]

There's a couple factors going on. One is the fact that Youtube's algorithm recommends videos based on a set of engagement-related metrics. Hitting Like/Subscribe is a big measure of engagement, but according to people do this for a living, the most important metric is watch time. This is true both for the video _and_ your channel, so having a lot of long, fully watched videos will cause your channel and its videos to be recommended more often.

The second factor is that one factor you get paid on as Youtuber is video length. Getting people to watch longer videos makes your revenue go up.