Avoid shifts in pronoun forms - Ten ways to avoid grammatical errors

100 ways to improve your writing - Gary Provost 2019

Avoid shifts in pronoun forms
Ten ways to avoid grammatical errors

Be consistent in your use of a pronoun. Do not switch from singular forms to plural ones.

Inconsistent

Consistent

After a student has written a paper, they should take a break.

After a student has written a paper, she should take a break.