Okay, so I want to jump in that I have never come across the idea of choosing tasks randomly - that seems counter productive to actually getting things live.
But all in all I've also not really seen any workplace do "Agile" in remotely the same way as other places so who knows. But also Agile isn't something about a "lack of documentation" ... keeping well documented software is one of the key aspects of making Agile work, so your software should be documented.
Of the places I have seen working though documentation is often pretty damn lacking, and it makes picking up projects from someone else a nightmare. This part is a regular thing in software development, but you can help by actually writing docs for things you pick up (there are also tools for auto generating docs all over the place).
But yeah, the "Planning Gambling" is not something that I have come across, and would probably be pretty strongly against unless someone could give me a pretty slid list of reasons to why it would be beneficial, so this part as least is not exactly typical of workplaces.
tl;dr Agile gets done very differently in different companies "Planning Gambling" is something I've never seen before, but lack of docs is often fairly common from experience.