Being Diligent.

In a world growing more and more dependent on the use of cell phones, one needs to realize that "hitting someone with that no reply" is something that should be left in middle school. I understand that sometimes getting you point across to some one can only be accomplished by ignoring someone, and in some cases it is perfectly acceptable. But as you age, the conversations where points like those have to be made will slowly decrease. You may still have the random creepy person that got your number from a friend of a friend, and the random strangers that "slide into your DMs", but other than those exceptions, replying is the mature thing to do. For instance, when you get a job, and someone asks if you can cover a shift, reply no matter what, even if you do not know or know that you cannot. It is just common curtsy, and you will understand the annoyance of slow-repliers when you must have a shift covered. The people you work with will also think better of you if you are on top of things when it comes to your schedule, so always keep it organized and never hesitate to take a shift when you can, you never know when you will need one covered on short notice.
Back to replying; in high school, there are many circumstances you may run into where you get into disputes with your "friends" and talking to them is the last thing you want to do. Let me give you a bit of advice, if they decide to be the bigger person and text you, text back. And if they decide to give you the silent treatment, be a good person and try to make amends. Fights are honestly not worth your time, and not replying to someone is no way to solve anything. Be the person who is the quickest to respond because it makes everyone's day better.
One last thing to remember, if someone is doing something for you, giving you a ride, inviting you to something, covering a shift for you, giving you homework, make sure to make their messages a top priority. They are going out of their way to do something for you and they deserve the fastest reply your fingers can type. If you take my advice on this, fewer people have the chance to get mad at you and therefore make your life easier.
JSL