I like my battery to last a whole day, pretty please. Whenever on mobile and AMP is not an option, I'll try Firefox Focus. If that doesn't work, I'm as likely to move on as to revert to letting the site's affiliates run Javascript on my phone.
Anecdotally my phone is about 4 years old maybe and the battery still does fine browsing with JS on in Firefox mobile. That is with ublock though.