My thinking is that if you're getting bored on a 3 min stop then you aren't thinking about how to improve your diving.....
Nice point.
I just said this on another thread, but perhaps it would be helpful to repeat it here. When I was a brand new diver and struggling to hold a safety stop, I was in awe of the DMs who held the stops without moving a muscle. I vowed I would do the same. Even today when I am doing a NDL dive with a 3-minute safety stop, I focus on my depth and try to hold it precisely through breath control. Those 3 minutes of practice every dive have done me a world of good.