I have worked in jobs with time clocks and those without. The ones that
I had to "clock in" were in other than the health professions.
If technologists are to be regarded as professionals then I do not
believe that time clocks should be used. To me this indicates a failure
of the work environment. If individuals are consistently tardy then it
is the job of the supervisor to deal with this on an individual basis.
Making a rule that all have to punch a clock merely shifts the emphasis
from a one person problem to a blanket rule that ends up penalizing all.
We need to have rules in existence but having lived in Texas for 14
years I like the attitude we adopted Texans have seen of "it's a guide".
If you have a good employee then there must be some flexibility in the
system to allow them to have a day off to attend to family business even
if they do not have any vacation time left. This is because you can rely
on them to stay late if you really need them to. 
It is difficult to generalize about overtime and comprehensive time.
Expecting people to stay late on a consistent basis indicates to me that
there is an underlying time management failure or insufficient staffing.
If it is expected and agreed to in the job there must be some
consideration given to also giving financial compensation for this.
Barry