よく and 多く: frequent actions and a large number of people
Compare one person’s frequent library visits with visits by many people, keeping frequency separate from head count.
How often an action occurs
よく can express frequency. 私はこの図書館によく行きます。 says that the speaker often goes to this library.
週末によく料理します。 says that the person often cooks on weekends. Identify whose action repeats and when it occurs.
A large number or amount
多く, read おおく, can express a large number or amount. 多くの人がこの図書館を訪れました。 says that many people visited this library.
今日はいつもより多くの本を借りました。 says that more books than usual were borrowed today. The greater quantity concerns books, not the number of visits.
Read よく with the following action
よく読んでください。 can ask for careful or thorough reading, depending on context. よく does not always specify reading something repeatedly.
The information in よく図書館に行く一人 differs from that in 多くの人. The former concerns one person’s visit frequency; the latter concerns the number of people.
Does 多くの人がこの図書館を訪れました。 mean that one person visited frequently?
Show the answer and why
No. It says that many people visited. The number of visits made by each person is not specified.