if i'm doing a BIG training block (ironman, 100 miler) that is 5-6 months, i usually build in a mostly rest week somewhere in the middle of it. Its more a mental rest than physical, but helps prevent burnout.
Back when I was lifting a lot and regularly, I would take a week off every few months. Same as above, it was as much or more of a mental break than physical, but I always felt like I came back more focused and stronger.
I can't even remember the last full week I took off.. even vacations we find gyms to drop in to everywhere we go.
I take a day off about every 2 weeks because some part of me is overly sore and I know I shouldn't do much.. but even those days I normally run and stretch.
Going to Mexico in a few weeks, but we've already located a gym to visit.. 7-day backpacking hike in August, that'll be a full week of no barbells