Is full control effective?

Any organization, whether it is a hardware store or a full cycle advertising agency, usually takes some measures to control the activities of its staff, from the executive director to the downstream seller.
The purpose of this is to obtain the maximum result from every minute spent by the employee in the workplace.
In stores, the working hours of sellers, their lunch hours, smoke breaks, etc. are monitored.
In IT companies, in addition to the above, the Internet resources that are visited by employees are monitored.
There are sites whose visit is severely punished by management.
Also, there are companies where the Internet is completely closed, allowing entry only to specific resources for each individual row of workers.
Is it correct?
Personally, I can not work normally, if I know that I do not have the opportunity to escape.
It is also very unpleasant to realize that your monitor is being scanned through radmin.
Do such restrictions allow the staff to work efficiently over a long period of time?
Maybe it makes sense to give them access to icq at lunchtime, or, secretly from them, to open vkontakte.ru for a couple of hours, so that they can rejoice, thinking that no one knows?
Perhaps the most effective strategy will be a contract for work on the result with the interest rate from the completed project.
I, nevertheless, believe that cruel control negatively affects the motivation of employees.
And the tacit provision of small network joys, even if it reduces productivity by a few percent, but for a period of more than one working day, you won’t lose a trained, competent employee just because he was tired but could not be distracted.
Any points of view are interesting.