QUESTION:  I have one student who refuses to learn even the smallest brief.  She insists on stroking out if you, I couldn't, I don't, I didn't, I know, did you, etc.  She is in her 120s.

ANSWER:  I don't push briefs and phrases on students.  Many times they are more trouble than they are worth.  What happens is that students try to use those special strokes before they know them.  That causes hesitation.

Generally, I tell students to balance the work against the reward.  In other words, I want them to work on the words that show up the most.  For example, if they learn Phrase A, they will be able to use it 20 times a day.  If they learn Phrase B, they will use it only once or twice a week.  So I tell them it would be better to learn Phrase A.  They should concentrate on the common briefs and phrases.

As to your student, she should know some briefs.  There is no reason for not learning the common words and phrases.  She is one of the few students that needs to be pushed towards learning briefs and phrases. 
I do not use the brief for "CONSEQUENT."  I know the brief, but I get it confused with the stroke for "SUBSEQUENT."  If I use that brief, I hesitate and stumble.  If I ignore the brief and write out the word, I write strong and clear, albeit a tad bit slower than those who use the brief.

I have a good reason to get rid of that brief.  I tried it, and it doesn't work for me. 

Your student appears to be dismissing all briefs and phrases without trying them first.  She is saving time right now because she doesn't have to learn them.  But she will be forever putting in extra time writing simple briefs and phrases such as, "automobile" and "at that time." 

The concept of writing a short form of a word should not be alien.  The very essence of stenography is that we can represent words in a minimum of strokes.  She will save herself a lot of work on future drills and tests if she will work on the popular words.