@silverknyaz: They're supposed to :p From the 1.0.4 patch notes:
* Exploration now spread to the adjacent subcontinents after another X years
* How quickly exploration spreads now depends on which age, as it goes faster with each age.

did they? i've never seen it

@silverknyaz: Areas, for performances sake :)

Of course, Paradox added discovery spread in the very next patch, in a slightly different way :p

discovery of... what? provinces? areas? institutions?

woah, this looks really cool. Is it kinda busted with its speed being fast with both your version and vanilla spreading?

brilliant

Yes! Vanilla Spread apparently goes from region to region after a set amount of years, working like EU4's from what I read, while this one has a small chance of discoveries spreading from market to market depending on cultural and religious views. So they work differently.

Activating this will currently enable both of those discovery spread methods.
I should probably add a game rule allowing you to select which option you'd like, but I haven't checked if you can even disable the new vanilla spread option from firing!

Any difference with the newly vanilla added spread?

@DanielAir I've tested this mostly in debug mode on full speed, since it mostly becomes a thing after Age of Discovery, tabbing between countries to find the right balance, so my results will be skewed.. But it seemed fine to me, but of course I'd like confirmation from others :)

And thank you, @Silver Knight!

Added to the EU4 missing systems thread: https://forum.paradoxplaza.com/forum/threads/eu5-missing-features-thread-eu4-systems-mechanics.1869193/#post-30895177

Nice! Is the performance hit significant?