To be efficient, it is helpful to understand some game mechanics. For example, Restart Points/Control Points and Save Points.
Last one is a special control or checkpoint, which offers you a lot of opportunities.

Checkpoint:
You can prevent death when you hit Esc-> Restart while dying and you will continue from the last checkpoint, however what you collected is gone. Doesnt work when instakilled. Easy on Solo, bc game is paused, tricky in coop, needs practice. Please note that only the host can restart. When you restart from a checkpoint, your inventory will always be resetted to with what you started at this point, no matter how much loot you make until you reach the next saving point.

Also, you don't have to run through the whole chapter with your full inventory, desperately thinking what to take with you and what to throw away. Simply rearrange it after every checkpoint! Hit Esc-> Restart. Voilà! Please please keep this in mind when hosting a CoOp! Your Partner will be grateful to have access to the inventory as it is sometimes necessary to change weapons.

Save point:
If you exit the game and save progress, you will restart from the last save point. Of course the beginning of every chapter is such a save point, but you will come accross other save points during your run. Just keep an eye on the upper right corner, what type of point you reached, usually behind doors where both of you and your partner need to get through. When "Saving" appears its obviously a saving point.
Since you can choose to save your inventory when exiting the game, you can farm stuff from the beginning of a save point as far as you want but before reaching the next control point, exit the game and repeat.
Works everywhere in the game. And of course, treasures can be farmed this way,too!

Enough theory.

Here we go, endless Money and Ammo for you! Riches to the rich! Bath yourself in green Herbs! Just a short excepts from what i found useful (will add more if useful):

Chapter 3-2
Oil field -Docks (last segment, the one with a countdown before jumping on Josh's boat)
This is the most efficient and satisfying one in the game!
No enemies! Just run accross the map,trigger the cutscene, turn around, loot the suitcase in the left corner, save&exit, repeat. Boom. 3000Gold in 30 seconds. 6000 when playing on pro. Thats pretty neat, isnt it? If you like, take the 3 barrels with you on your way.

Chapter 3-3
Irving Boss fight
Turn around, run to the corner on the right, grab the First aid Spray, save&exit, repeat.

Chapter 5-2
last Segment before Uroboros Boss fight
Grenades for your grenade launcher in the crates. Enter Uroboros fighting area. Loot everything, save&exit, repeat. Grenades, Ammo and 2 First aid Spray. (yes 2 , one is easy to miss)
Oh and don't forget to get your free Rocket launcher from the Shipwreck in the middle of the lake from 3-1. You will need it here. Trust me.













Chapter 6-2
Excella/ Uroboros Boss Fight
Good for farming herbs and grenades. When you solo this one, abuse your Partner as a backpack. Just dont give him a weapon. If youre running out of Ammo for a special type of Weapon, Shotgun or Rifle, just put a weapon for what you havent bought unlimitied ammo yet in your inventory and play this chapter. Kill as many small black uroboros offshoots you can until your inventory is full with nice stuff. Works best with infinite Ammo turned on, Magnum and Hydra. Can be endlessly repeated with a coop Partner if you dont kill the big orange ball at the end. Again, save&exit, repeat.






















There you go. Have fun! Hope you find this Guide useful, even if youre playing already speedruns on pro ;)

Cheeers!

Note:
In RE4 it was easy to avoid enemies dropping unwanted ammo but money instead, you just needed 100 Handgun Ammo in your inventory. RE5 mechanics work different. Its random if you get money or Handgun ammo. Didnt find out how this mechanics work so far.