On a technical point....
Commercial airliners are not at all likely to be holding at 300kts. This kind of speed would make the holding pattern extend way out and interfere with other airways. Furthermore, unless explicit authorisation is granted the blanket rule worldwide is 250kts or below at 10k feet and under.
The most likely speed for holding is a healthy, economical, no flaps 220. Anything from 190-230 actually is the most common speed for holding.
Biting the hand that feeds IT
