I am in a startup. When necessary, yes I will put in extra hours. What does ‘necessary’ mean? I report directly to the big boss and he always insists I don’t h

I am in a startup. When necessary, yes I will put in extra hours. What does ‘necessary’ mean? I report directly to the big boss and he always insists I don’t have to work outside of regular hours. But there are times when other team mates are depending on me for something and through external forces (customers, opportunities) they have an expedited timeline, I’ll choose on my own to kick some ass for a few days and help them meet their goals. I am abundantly compensated for my efforts by the company. And the big boss has always recognized my contributions and sweetened the deal for me. There are also times in normal mode where we have planned things and I underestimated time requirements I will kick in to maintain my reputation. Other times team mates can wait longer and they recognize our dynamic environment and they’re chill about me being “late” on something.