If you can build 4 months (or even just 3) of runway on 1 month of salary, it doesn't take long to get a really good buffer in place.
Anyway, it takes longer than you think, especially if you had to relocate to take the new job. Once you take into account paying off that type of stuff, paying car insurance, car payment, funding your 401k, etc, you’ll be lucky if you can buffer one month for each month.
Maybe I've read too much FIRE financial independence content though.