Whether I'm "supposed to" do this is another question (that I'm not seeking opinions on here) - but....
I find that with the Diva Cup - I'm good 8-12 hours (and I've inadvertently gone a bit longer than that). I usually only get leakage with an empty (and try to have wet wipes handy). So, I don't wear anything with the shorts - but I don't tend to leak and I wouldn't empty on a 60 mile ride. I've tried riding with panty liners, etc. at the beginning/end of a period and it has been a disaster for me. I think I might rather just use spot remover on the shorts....
Most days in life don't stand out, But life's about those days that will...