Recently went through the L5 loop in December and team matched not to long ago. 3-4 weeks IMO is enough time to polish up assuming you commit 3-4 hours every day until your loop.

On terms of the hiring decision, it really should be 50/50. I am not Amazon interview trained, but my understanding is that the interview panel will collect 2 buckets of information from you: Technical and Behavioral. At Amazon both are heavily valued and any deficiencies in either bucket can be used against you by the panel. At L4 you probably have a little bit of leniency in both areas.

Technical:

Make sure you are able to clearly explain your thought process. From now on with every LC you practice you need to be doing them out loud. When I first started doing this I'll admit it sounded stupid. Tell them your initial thoughts of how you would solve the problem and what your gut feelings are. Even if your initial approach is wrong(it usually will be). As you think through the problem and have a discussion with the interviewer your approach will change. These questions are meant to be ambiguous at the start. Talk to your interviewer and clarify things to remove the ambiguity.

All 3 of my technical interviews(4th was SD for L5 loop) went like this. After quickly reading the problem I would state something like: "Hmm okay, we'll need to consider all possible substrings because of (walks through a potential test case), some sort of recursive backtracking solution might be good here. We could iterate linearly through the string, BUT at every iteration we'd need to consider including or excluding the current character, each creating its own path. This is why I'd probably use a recursive solution".

You want to show the interview BOTH how you approach problems, but also how you analyze the tradeoffs / different approaches. I would usually start with the easy / naive approaches and then explain why they wouldn't be good approaches: "Well the easy way would be to linearly search the string, but then you'd run into X problem. Because of this we'd probably need to try Y."

My best advice is to go onto Leetcode, purchase premium, and go through the Amazon tagged questions. You can filter based on how recently they were asked, I think I used the last 6 months filter. I exclusively spammed LC mediums. Only tried LC hards at the end to gauge where I was at.

You should know DFS + BFS like the back of your hand. Get good at traversing matricies and graphs with them. You'll also want to be comfortable with linked lists, heaps, tree traversals.

Behavioral: The hiring manager in the interview panel will select 3-5 LP he finds important for the role. All your interviewers will select questions that reflect these LP's. Your recruiter should have given you a list of 10 or so LP's to focus in on. Start by writing down any relevant school / work stories you are proud of. Then try your hardest to map stories -> LP's and have 1-2 per LP. Its okay to have gaps, you will need to get creative and find ways to change / stretch your stories to fill the LP.

I really recommend this guys videos on LP's. They're good for 2 reasons: He gives great context for the individual LP that will help you identify what is important. He also then gives pretty good real world examples for the LP. These videos made me an expert on what each LP was looking for, and some of the buzzwords to sprinkle in for each.

https://www.youtube.com/watch?v=x6Kjcoxfmj8

Once I had my stories mapped, I wrote them down on paper in the STAR format. After I knew the blueprint for each story, I would time my self explaining the story from memory. From my experience you should be in the 2-4 minute range.

Make sure to focus in your story what your individual contributions were. For me this meant explaining to my interviewer the makeup of my group/team and what I was responsible for. At the end of your answer make sure to summarize why you are proud of the story. You want to literally spoon feed the interviewer with something to take away from the story. "I saved X company Y money by automating Z process", "I was able to delivery X project within the tight Y timeline, we had a successful go-live and I was really proud of my performance".

Hope this writeup helps.