Mana Burn is gone, yes, in terms of doing damage, but players' mana pools still empty after each phase.
My best decks started with the "rule of 1/3", and added/trimmed 1-2 lands to optimize. The "rule of 1/3" is that 1/3 of the deck should be lands, for best land draw. So a 60 card deck would start with 20 lands, and maybe swap 1-2 forests for elves in an elf deck.
And from a recent card randomizing thread, it takes 7 "riffles" to fully randomize a deck.
Conventional wisdom suggests going for around 40% lands. So 24ish lands for 60 card decks, 17ish for a 40 card deck.
Having more than 35% lands leads to the very mana flooding complained about in the root comment.
https://www.channelfireball.com/articles/how-many-lands-do-y...
With 35% lands (21/60) you are likely to end up mana-screwed (not enough lands) unless you build your deck to match the low land count. For a generic rule of thumb I think it is better to recommend a bit more lands than that.
>And from a recent card randomizing thread, it takes 7 "riffles" to fully randomize a deck.
I don't think you understand what "randomize" means. It doesn't mean "you get proportional hands", it means that the state isn't predictable. It is still subject to variation in the amount of mana you draw.
Seriously, you are reciting trivially basic concepts, that everyone is aware of, and completely ignoring and/or misunderstanding what is being said and the real situation.