I have a close friend who only used condoms in college for birth control, he used them everytime with his girlfriend. That said it diod nto work and he had two kids with her, bith were not planned. He jokes that fertility clinics are not needed all you have todo is get a box of trojans.
You only have to look at Africa to see how effective condoms are. They have been heavily distributed there for many years and tet there are no signs that they have made a dent in preventing the spread of STD’s.