Do you know what I am not one of those kinds of people who expect an answer straight away, I hear my sister say sometimes, oh I text my boyfriend like 5 secs ago and he hasn't replied! and I'm like seriously give the guy a chance..
If I sent some guy a text and he didn't reply and a week went by, then I would think something was wrong and wouldn't bother trying again, he'd have to contact me. BUT if a text came through the next day well it wouldn't bother me.
And what's more there is an easier way round this subject. If you know someone enough to know their routine, if you text them and they do not reply, ring them, and if they then don't pick up...wait a while to see if they make any contact...if they don't then they are clearly wasting your time, so why waste theirs.