Love you work elisavetasivas and I agree with everything in this thread so far.
It seems you may be noticing a few people in your activity feed repeatedly. That is their promotion work for their shop. If you are annoyed by certain seller's activity you could always remove them from your circle so they don't show in your feed, but you may want to check out what they're doing and emulate their methods to promote your own shop.
As far as the time factor, it is very time consuming to promote. I've found marketing is better for me in the morning and because I'm really a night owl, I create late. Usually after morning promotion, the sun is right for photographing my work from the night before. In the afternoon, I put new listings up, make treasuries, work on team stuff.
I would encourage all Etsians to check out this newsletter for great tips for marketing your Etsy shop. Its free and I've found it very helpful. Also sign up for the Etsy newsletters, they have great info too.
http://marketmyshop.blogspot.com/