This question has no universal answer and I'm a little tired of posts that pretend it does. So here's an honest framework instead.
The honest factors to weigh:
First: do you have runway? Conventionally people say 6 months. I'd say 9-12 if you're in burnout recovery because the first 2-3 months you may not be search-ready, and in 2025-2026 market conditions, searches routinely run 4-6 months. If your runway is 3 months, you cannot do this without significant financial risk.
Second: how bad is staying? There's a spectrum. 'I'm tired and demoralized but functional' is different from 'I am having panic attacks before Monday morning.' The former you might be able to hold together while searching from a position of employment. The latter is actively damaging your health and you need to get out.
Third: what's your field and level? Senior tech roles with some brand-name history on the resume tend to search faster. If your experience is specialized or mid-level in a slower market, add time. This affects the runway calculation.
Fourth: what's the recovery actually for? If it's 'I need to sleep for a month and then I'll be ready to search,' that's different from 'I need to fundamentally reassess what I want from work.' The second one needs more time and space.
My own experience (ex-MBB, now corp strategy): I quit a consulting role without anything lined up in 2022. Had 8 months of runway. Took 5 weeks before I felt like a person again, started searching in month 2, landed something good in month 4. Net outcome: positive. But I was extremely lucky with timing relative to market conditions. I would not make the same move in 2026 without serious financial cushion.
The people I've seen regret it most: left with 4 months runway, took 2 months to feel ready, panicked about money, took the first thing offered. Wasn't the right thing.
This is a financial decision first, a health decision second, a career decision third. Run those in the right order.