Is it possible for startup founders achieving WLB?

I can only share my experience, with a small sample size of two 😬 Both these startups were started in the same year, both in Silicon Valley. Startup A - I was the 2nd engineer hired. The company had an explicit "we can have great WLB and still succeed" mantra from one of the founders, who had been burnt out by a previous startup (they IPOed but it was extremely stressful). Nobody (not even the founders) worked past 5pm, never on weekends, and everybody took about a week of vacation every quarter. The company grew slowly and surely, struggled to raise funds at one point, but are now a solid Series D company. Startup B - I was about the 300th engineer hired. The company had an "always on" culture, stemming from the founders. We routinely worked to 11pm - 1am, often on Saturdays, and very rarely on Sundays too. I am guessing the founders did not pause on Sundays. The company IPOed about 3 years ago. So I think it is possible either way. But who knows if Startup A would have grown bigger and faster (if that's what you want) if they just went all out - it's highly dependent on market conditions too. I do know that Startup A's founders have a financial outcome orders of magnitude less than Startup B's founders (again, if that's what you want).