And now an estimation of the number of pack you'd have to buy using an optimized way
(slightly less precise than the previous method because of complexity)
-191 pack recruit
-230 pack veteran
-200 pack spectre
and if you want every ultra rare items, you'll need 700 spectre pack instead of 200.
First of all, we're going to forget Ultra rares items. It makes 17,555,000 credits to get, which represent 250 gold games, 585 silver games or 1170 bronze games.
That is approximately 125 effective hours of gold game, 243 hours of silver or 292 hours of bronze, considering that you'll need 30 minutes for a gold game, 25 for a silver and 15 for a bronze.
Everybody knows the gold difficulty, and succeeding in 250 games without making any silver or bronze one is almost impossible. And with the time you'll spend upgrading characters, bad groups, failures and the time in the menu, you'll probably need something like 250 to 300 hours. And if you're unlucky, then you can give up right now...
Let's imagine now that you hope to unlock everything, 47,555,000 credits will be necessary, which is 3 times more credits, so 3 times more time... a thousand hour on Mass Effect 3 would have been a pleasure, but unfortunately, it does not offer this length of life in multiplayer, but rather something like 50 hours without DLC right now.
But wait, maybe if you buy a few thousand euros in Bioware points, we could get all of this. It must be the solution !
This Crate unlock system is probably one of the dumbest they ever implemented. Thank god I bought this game for the Single player.