Ever.
If you own a site, just curate a set of ads on your site that actually enhances your sites appeal. A fashion site should have matching fashion ads. A tech site should have matching tech ads. A local site should have matching local ads. Reach out to advertisers to get these ads. Never use an algorithm. You, as an editor, should be better than the algorithms. Ads are supposed to be useful to your audience, instead of being annoying. People buy fashion magazines - filled with 600 pages of ads- and Sunday newspapers BECAUSE of the ads. They should want to visit your website as well because of your ads.
The worst thing you can do for your site is to place out-of-context ads in the middle of your site. Can you imaging if Vogue.com decided to place Flash SSD ads on their site? This is how you destroy an audience, and as a publisher, your number one concern should be to grow your audience.
Once you curate a set of ads for your site, you'll find that click-through rates and conversion are far higher than random programmatic ads. You should know your audience, and the kind of ads that would appeal to them. Mark ads as content in your CMS. This avoids ad-blockers.
Curating ads is how advertising has always worked, and will continue to work, after all these programmatic garbage goes away.