Can being late with taking the contraceptive pill by a few hours weaken their effect?

You did not write what pill you mean. As for the Vines preparation tagged on the question, if taking the pill is delayed by less than 12 hours, contraceptive protection is not reduced. The tablet should be taken every day, every day at about the same time. The interval between individual tablets should therefore never be more than 36 hours (every 24 hours regularly plus a maximum of 12 hours of delay). It is best to stick to the chosen time, although the tablet does not need to be taken "with a watch in hand". The manufacturer shall only provide information on the maximum delay and shall not include data from studies on how taking the tablet daily at different times affects its efficacy. Ideally, large differences in the time of taking the drug should be sporadic and never exceed the designated window. I enclose additional information: https://www.gdziepolek.pl/artykuly/jak-prawidlowo-stosowac-antykoncepcje https://www.gdziepolek.pl/artykuly/jakie-leki-oslabiaja-skutecznosc-antykoncepcji