I have used the ads for a week, then turned it off, and used them again for a few days. I had a few clicks, but that was it.
I had it on $1 per day and on selected listings only.
Then I did some research and found, that for what I am selling, mostly sellers with low or now views were using the ads. At least for the searches I used.
It appeared to me, that well established sellers with lots of followers, admires and lots of sales, do not need to use those promoted ads and pay. They are selling anyhow.
I rather did renew some of my listings to put them on more recent search results again and I did find myself on the first or second page in the searches I did.
I also search for my items in a different browser and not being logged in. That way when I find one of my items and I look at it, it counts as a view.
But I don't renew every day or too often.
I have so many items to list, that right now I am concentrating on that and I often read, that more listings help also in being found.