Quitting a job to get time to prepare for interviews

So here is some background information for some context: - Am 25 yrs of age - I live in a developing country(if that matters) - I finished my studies in 2020 but graduated with a degree in computer technology in 2021 due to Covid - But I started developing real world applications in 2018, due to financial issues. The freelance contracts I got around that time, helped alleviate my financial woes including paying for my fees. - Got my first permanent software job at a remote startup in a developed country in 2019 and been working there ever since as one of the founding developers.

But now I have been interested in getting another job for some time due to a some issues affecting me in the current company: - Working on some weekends, frequency increased in the past 8 months - The boss claims he will give me a weekday replacing the weekends worked but most of them are not replaced(giving an impression am working for free) - Occasionally, there is always a deadline leading to working 12 hours+ to meet it - The long working hours and weekends got so bad that I got burnt out and tried to quit a few months ago, but boss told me he will replace them but the bad patterns have already emerged again - Changes in some of the clauses in the contract or per what we agreed without letting me before hand. - I suggest we follow best practices but the boss is more focused on how many features we can develop, tasks we can do.

I have applied to a couple of jobs(on and off) in that span of time and although I was able to get them to have a call with me or get tested for my skills, I often failed the technical assessments due to lack of enough preparation(since most of the time am working and rest when I am free) Also I see most jobs either requires to have experience in distributed systems(which I have no professional experience) and use industry standards to write software(which we never followed). This makes me feel like I need to learn even more things in order for those companies to see I am experienced and its not just fluff.

The current job limits my time but I want to grind hard on various technical questions so that I can be considered for any role and at least reach the offer stages. I also have 4 months reserves to sustain my current lifestyle. I also heard you are more likely to get a job while you are on a job. Now comes my question, should I quit my current job then I practice for interviews to increase my chances of find a better job?

Also any help on how to prepare for interviews and crafting a very attractive resume would be appreciated. Thanks!