I had about 20 people (out of 97) miss the RSVP date. Most of them sent their cards back just a week or so late, after a call or an email from my mom, FMIL, or me. The remaining few I really had to chase after. I just got an
answer from the last person I needed; she kept telling me she wasn't sure if she was going to bring a guest or not. Another friend of mine emailed me to say she coming, but didn't tell me whether she wanted chicken or beef. I kept asking her,
but she just kept saying, "Of course I'm coming to the wedding!" and asking me about other things. I finally put her down for chicken and called it a day.