Do you know the difference between a rhythm and a beat? Don’t feel bad if you don’t. As simple as it should seem, the truth is that not everyone knows the difference.
Not every bar in an 8- or 16-bar progression needs a different chord; it’s about balancing variety (things that are different) with unity (things that repeat).
Another common way to create more interesting chords by altering the notes of the basic triad is to form what are called suspended fourth chords.
It is entirely possible to have a long, successful guitar career without much musical theory knowledge. But, theory is great to know for a variety of guitar-related tasks and activities, such as songwriting, teaching, and accompanimental playing.
The most common and most useful of these chords is the seventh, which you can use pretty much anywhere just to add a slightly different color to a chord, or in some types of progression to give the sequence of chords some extra thrust, because the added seventh is a mild dissonance, or clash, that makes the chord sound like it wants to move somewhere.
Chromatic alterations, such as sharps and flats, can be used to help create a more interesting chord progression in a piece of music. Ed Bell explains how to use these alterations effectively.