If your CFI has you doing 45-degree base turns as a new pilot, then he is instructing you incorrectly and you should find a new instructor.
Final approach in any aircraft is supposed to be done at a 3-degree glide slope and if you are turning base when you are 45-degrees from the numbers, then there is no way you will be able to do that (unless you were to make a very steep descent onto base which is improper). Your instructor should be having you do 3-degree finals, which requires you to be out about 2000-2500 feet out and having an altitude of about 100-120 feet when you turn onto final. You are required by FAR 91.87D(3) to follow visual indicators such as VASIs when you land, which means a 3-degree glideslope at most runways, so your CFI should be doing 3-degree landings exclusively when you are a beginner. If he is not doing that, you should get a different instructor.
I recommend that you work out the math so you confidently and completely understand the geometry of a landing. Here are the key constraints to be aware of:
- Airspeed: 1.3 x Vso (FAA recommendation) minimum
- Do not descend faster than 500 feet per minute
- Maintain a 3-degree glide slope on final
(Note that the VASI at your airport will probably be set to a 3-degree glide slope unless your airport has unusual terrain.)
Work through the math to figure out where you should be to meet these basic requirements. If you do that, you will find that your instructor is teaching you to do steep descents on final which he should not be doing until you are more advanced. As a beginner you should always be doing 3-degree glide slopes.
Experienced pilots in small aircraft often do steep finals to land fast, but you should not be learning that until you are a lot more experienced and have soloed. It is both potentially dangerous and improper for a beginner to be doing steep finals.
As for the other pilots in the thread saying that you should be rushing your finals so as not to delay the other pilots in the pattern, ignore them. You should be learning the RIGHT way to fly and the jerkoffs in the Extras behind you will just have to wait.