When you say a redundant phrase, you are just repeating yourself. How many of these redundancies are you used to hearing or using?

cacophony of sound - A cacophony is a harsh and meaningless mixture of sounds. It is not a harsh and meaningless mixture of anything but sounds.
A cacophony of sound filled the auditorium and made it so obvious that the band had not practiced.
A cacophony filled the auditorium and made it so obvious that the band had not practiced.

CAD design – CAD stands for computer-aided design. So, if you say CAD design, you are really saying computer-aided design design. Is that something you really want to say? Do you want to be known for repeating yourself?
Marsha wants to study CAD design in college.
Marsha wants to study CAD in college.

came at a time when - The prepositional phrase 'at a time' makes this expression redundant. 'When' is a word that points at the time of occurrence.
The news came at a time when it was needed the most.
The news came when it was needed the most.

cancel out - When you cancel something, such as a newspaper subscription, you do away with it and it just disappears.
Please cancel out my membership in the club.
Please cancel my membership in the club.

careful scrutiny - Scrutiny is defined as a close and searching look. Whatever you are looking at in scrutiny is being looked at in minute detail. How much more careful can you be?
The author did her research with careful scrutiny.
The author did her research with scrutiny.

cash money - Cash is money. Money is money. Why would you want to say both words when one is sufficient? I can understand that maybe a person would think that there is a need for it to be clear they are using cash and not a credit card (plastic money). In that instance, cash would suffice.
The newlyweds used cash money to pay for their new furniture.
The newlyweds used cash to pay for their new furniture.

cease and desist - Cease means to stop or discontinue. Desist means to stop or cease.
You need to cease and desist from cheating on your tests before you are caught.
You need to cease from cheating on your tests before you are caught.