There are millions of Americans that have to "clock in" each day, when they begin their work, and also have to clock out during breaks for meals or rest, as well as to "clock out" when their shift is finished for the day. The thing about technology is that it is quite accurate, so that when you clock in or out, it really does have the correct time and since today's time clocks can be integrated in real time to a database that establishes comprehensive records for each employee, that information is actionable without the necessity of additional timesheets or similar. Of course, it is the employer, that has the last say, because employers monitor timecards and can adjust hours worked either up or down, to which, all employees as a matter of course, should compare their payable hours to their time sheet to verify that they are not being shorted hours. While there might be legitimate reasons why an employer adjusts a particular time sheet, none of this should be done without proper notification to the employee involved, even, for relatively minor amounts of minutes, as an employee deserves to be paid for every minute of work accomplished on behalf of their employer.
In most States, it is not the amount of time that you work in one day that triggers overtime, but whether or not you have worked more than forty hours in one week, so that on a given day, most companies do not care if you have worked a bit over or under your eight hours or not, as long as, by the end of the week, you do not exceed forty hours, without prior management authorization. This means, effectively, that companies are very good at making sure that they do not pay any unauthorized overtime, which obviously is a benefit to the company, but, on the other hand, they don't readily care, typically, whether you are short one or two hours of the forty that you are supposed to typically work in a given work. The person that should care about being short, especially if one is consistently short, week after week, is the employee, because those one or two hours each week of not meeting your allowable weekly allocation, can cost a person about $1000 or much more in gross pay over the course of a year, whereas the extra time that you have off, is seldom worth losing that sum of money.
The problem that a significant amount of people will have with time clocks, is unless they are very diligent in all their activities in regards to their labor by always starting their day at the same work time, taking their breaks and meals at the same time, and clocking out at the same time, sort of like a machine, they are at the mercy of a machine that has no give and take. That is to say, if you consistently show up a couple minutes late, clock out for a couple minutes longer at your breaks, and leave at shift closing time, because the company does not permit an extension to this, than you will as a matter of course end up short by a couple hours each week, by virtue of those "little nibbles" at your labor. While on the one hand, you can argue that one shouldn’t be paid for the work that hasn't been clocked in, what isn't often taken into account, is that the employer has deliberately "gamed" the system, so that you will come up short on your paid hours, but often produce the same output as other employees that have received pay for the full forty hours worked.