Rarely. I use NoScript and only enable it for sites I trust.
(Yes, I realize that’s not bulletproof because how much can I *really* trust a site but I expect actual wide-ranging in-the-wild side channel attacks to get on the public radar before they can reach me.)
(And that assumes such attacks are actually feasible and profitable.)
The social network of the future: No ads, no corporate surveillance, ethical design, and decentralization! Own your data with Mastodon!