How often to post during the day?

I've used the iconosquare stats to check when is the best time for me to post.
It happens to be between 8-9 am and between 6-7pm (GMT+2) for me and best day being on saturdays.

Not sure how worthy are those stats but I stick to them for now and post max twice per day.

10 per day. 9gag does it and they have 15 mil followers. It doesn't matter if the engagement drops after every post. More pictures = more people tagged = more followers obtained.