Yes, it's because it's limited to two failures. If you drop the first bulb at floor 50 and it breaks, you have only one bulb left, so you MUST not break it unti

Yes, it's because it's limited to two failures. If you drop the first bulb at floor 50 and it breaks, you have only one bulb left, so you MUST not break it until you have limited the possible range to 1, so you have to just incrementally test 1, 2, 3, 4, etc. If you went straight to floor 25 and it broke, all you know is 0 < x < 25, and you have no bulbs left.