Ah, I don't even get messages on my phone :D Only on Whatsapp and only by one person (I haven't had my phone for long and very few people have my number, and most of them live with me, soo...)
I try to respond to every message. If it's spammers, I block them. If it's friends or people in need of help, I answer or try to help them. Fortunately for me in this case, I am not very popular, so I get very few of these too. But I do feel an urge to respond ASAP to my friends because I have been in need before and know that it's annoying if a good friend is not picking up the phone just out of laziness or annoyment.