[hjkm]

It totally depends on the company.

If you know you won't be profitable for a while and require outside investment, then you need a longer runway as it can take a long time to raise money.

If things are going well, but you've built your business on a channel you have no control over, like facebook (and one change to their algorithm / one even cyclical change in costs can screw you - this happened to a 'previously' successful side project I created) then it's best to save as much as you can - at least if you want to / think you can find another channel.

If you're working on a startup and aren't planning on raising money, then sometimes a shorter runway is a good thing - i.e. you don't want to dedicate yourself to 'the wrong' project for years.

If you've found a growth machine and output currently equals 2*input, there's not much point saving money huge amounts today. Best to continue investing.

Sure there are tons of other scenarios.