How often did the high priest enter the Most Holy Place, according to Hebrews 9?

Answer: Once a year

Only the high priest entered the second room, only once a year, and never without blood.

“But only the high priest entered the second room, and then only once a year, and never without blood, which he offered for himself and for the sins the people had committed in ignorance.”— Hebrews 9:7 (BSB)