If people are a priority for you, then you need to just make time. No one is unable to spare 5 minutes to text back. You just have to sacrifice 5 minutes of something else, whether it's work, a video game, or a hobby.
If you can't spare that, then I guess accept that those people aren't that important to you.
The great irony is that when they aren't important, the response is quick and easy. Your poor choice of words can piss them off and you don't have to care.
A person I'm close to does this (takes days/weeks to respond to anything). Important as they are to me, I've basically written them off as someone I can rely on.
For example, when you take 24 hours to respond, the message you're sending is that the person is a low priority, regardless of what text you've composed.
People who feel that anxious about composing the best reply should seek therapy to help them tolerate the distress of doing things imperfectly.