openzeppelin-contracts VS systems

Lets look the events of Open Zeppelin’s ERC20 token contract:

ERC-777 is difficult to implement properly, due to its susceptibility to different forms of attack(opens in a new tab). It is recommended to use ERC-20 instead. This page remains as a historical archive.

This depends if you're writing a contract from scratch or using existing code. If you're making something new, then yes (recommend not to use THE most recent available, always better to go with tried and tested). For existing projects, never try to override the solidity version. This may be a pain with "@" imports - ideally everyone should specify the library version (e.g. https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v2.5.1/contracts/token/ERC20/ERC20.sol).

It has been an year and I haven't applied, only looked at the job posting requirements cause I'm currently in my 3rd of software eng so I haven't been able to focus on blockchain devel solely. I find the answer to your question to be similar to ML model building: any high school student can create their model using KNN, MLP, etc, it's a couple lines of code using sklearn, but they won't understand it to depth one would if they had studied the calc, linear algebra, and probability theory behind the ML methods. I threw myself into blockchain projects but after doing a couple and trying to read whitepapers, I felt I had no clue what was happening beyond my IDE so now I'm backtracking to cover all the fundamentals. Since this field is so new and valuable courses are practically nonexistent, group forums and textbooks are the best way to go. I am currently reading Mastering Bitcoin/eth by andreas, and princeton bitcoin book. Going to try to read https://toc.cryptobook.us/ over the summer. For distributed systems start with https://www.ucg.ac.me/skladiste/blog_44233/objava_64433/fajlovi/Computer%20Networking%20_%20A%20Top%20Down%20Approach,%207th,%20converted.pdf then https://github.com/sushantmane/systems. If your end goal is to be a protocol developer then cryptography is definitely a must but not sure about a daap developer, probably best to be well rounded. Cryptography is pretty fcked so I'm sure you don't have to be an expert.