According to international hotel management experience, what percentage of overbooking can be controlled?

Overbooking is when a hotel is expected to be full, in order to prevent some unguaranteed guests from not showing up and causing vacancies. In order to prevent guests who have no guarantee but verbally promise to come at a certain estimated time or who say that some REGULAR GUEST will not give GTD at all, that is, the prefix 1 in FIDELIO RSVN SYSTEM is changed to the prefix 2 For that group of guests, OVERBOOKING can overbook about 5% of the guests after the hotel expects OCC to be 100%. The details can be determined according to the market and the hotel's SEGMENT. For unguaranteed guests, when the OCC is expected to be 100% on ON DAY, RSVN wants to chase GTD. If it cannot be contacted or does not give any arrival information, it will only be kept until 18:00 on the day in accordance with international practice.