Best duration for YouTube Videos?

Hi,

I've been uploading above 5 mins but less than 10 mins and sometime above 10 mins but less than 30 mins. I get a lot of views around 1million in 1 week and the average view duration is around 2 mins.

Should I upload small duration videos for increasing the average view duration or above 10 mins. I've heard that above 10 mins videos shows you instream ads which pays really good.

Content I upload - Mobile Gameplay targeted for kids.

Thanks in advance for your suggestions.

Does not matter. It's about your retention rate, comments on the video & CTR rate (clickbate). If solely rely on adsense, yes ads play at 10:00.

How can you improve those?
Make the video interesting
Ask for an opinion, giveaway if they comment
And clickbate the title & thumbnail