Booking Monsters in the Bestiary

I understand that to get a monster in the Bestiary you have to hit a monster multiple times (as many as 60). Do all the hits have to be on the same monster, or can I spread it across several fights?
For instance. If I'm fighting a Blue Dragon, and hit the Dragon 30 times with the Bestiary. Then decide I'm a little too close to dying for comfort, so I kill the Dragon. Then can I go find another Blue Dragon and hit that one 30 times to get it into the bestiary?

I did some testing, and it seems like it has to all be on the same monster at the same time. I hit a bunch of evil trees over 20 times, but I didn't GET! it until I hit the same one 5 times. The wiki says that you have to hit it half the number of hearts of health that it has, and since my sword can kill them in just a hit or two with only six stars of strength, it couldn't have over 12 health, let alone over 40.