If the purpose of the filibuster is to make sure the minority's concerns are heard, it would be totally reasonable to limit the debate to two or three days. Or to establish timed vote requirements for cloture, like 55 votes on the second day, and 51 votes on the third day. Extending the debate beyond that has never resulted in more minority views being expressed. Instead most talking filibusters consisted of reading from cookbooks, the telephone book, and such. Manchin's concerns are BS.
We're flying electric helicopters on Mars yet you can't turn on your clothes dryer in Texas. That's because scientists are in charge of Mars, and Republicans are in charge of Texas.