Short-term memory capacity will effect the success of her studying if she is studying last minute, as in right before the test. There is only so much that can be absorbed into the short term memory and if she crams everything in 5 minutes before the test, she will not remember everything. If she studies the night before this will not be as much of a problem as she will have time to rehearse the information. She will most likely only remember the things that she went over close to first and last. This is the serial position effect.
That causes people to remember things better if they are at the beginning or end of a series or list. Catherine will only remember the first and last things she goes over before the test. She also has to worry about the misinformation effect. If she is studying with friends she can be susceptible to suggestibility from her friends who could tell her incorrect information that she will memorize wrong. Since she is studying the night before she will also most likely be effected by the forgetting curve, the decline in memory retention over time.
She will no doubt forget some of the things that she went over the night before the next day just as if someone was to look at a series of words once and remember them and was tested on them 15 minutes later and 8 hours later, they would score much higher on the test 15 minutes after. Her effectiveness also depends on her study methods. Information is more effectively encoded when chunked or aided by mnemonic devices. If she uses that to her advantage and goes over the information again to prevent the forgetting curve the she will have studies effectively.