Here's an example of an error I often see.
| White | 20 |
|---|---|
| |
| Blue | 25 |
| Position Id: 2wYAAOgJAAAAAA Match Id: cAkVAAAAAAAA | |
The first error, of course, is not even noticing that there's a choice between 6/off and 6/1 4/2. But there's a second error, namely not checking whether one has an even or an odd number of checkers left; in many cases this will dictate which play is correct. In the above position, 6/off is inferior because it wastes a pip, leaves gaps, and you still need three (non-double) rolls to bear off. Take one checker off the 4-point and 6/off becomes correct, because it's important to give yourself a good chance of bearing off in two more rolls.
By the way, the even/odd dichotomy here reminds me of post-Crawford cube action (free drop versus mandatory take). Probably I'm not the first to draw this analogy.