I travel extensively in Texas, Oklahoma, Kansas, Missouri, Illinois, Indiana, Michigan through Spring, Summer, Autumn. Agricultural areas are worst for bugs that won't make it over the vehicle in the slipstream; August is probably worse than July, morning and night is worse than mid-day (most bugs need calm air to usefully, daytime on the prairie tends to be windier). There have been times driving at night with locusts swarming that I've had to stop to scrub the windshield three times in two hours of driving through wheat or corn fields.
I run two different vehicles, a Honda Fit and E-350 van. The van smashes a lot more bugs on both grill and windshield, but not many get through to the radiator. 35 years of driving in the region, have never felt a need for a bug screen, don't see anyone else using one. It is easy enough to see if there is an accumulation on the radiator and wash it off, maybe a couple of times a year.
There is a lot more use of front end bras than bug screens, mostly on the nicer cars, because bug juice can eat into the paint pretty quickly. If you put a screen over the radiator opening, keep in mind that one fine enough to catch small bugs will cut airflow by more than half when clean, much worse when clogged with bugs, so you'll have to keep cleaning the screen.
Tom Test
Itasca Spirit 29B