It is hard for people who are not controllers to understand busy (and for some who are, as well). The frequency can be busy, without you being busy (a lot of not complex traffic). The frequency can be quiet, and you can be flat out with coord, or with a few aircraft requiring a lot of watching/sequencing/not doing what they are supposed to. Complexity plays a huge part (lots of climbing/descending crossing). Or even what equipment you are working with (I have seen some amazingly complex, super busy non-radar towers doing their own procedural arrivals- put a radar in and you wouldn't look up from the newspaper
). Yet some terminal guys at THE biggest airports think they work hard because they talk to a constant stream of pre-sequenced same type a/c.
Almost everyone works near their maximum at some time- otherwise a manager shuffles the deck chairs until you do.