Crap, you're right about my math (I went full tard and divided 500 by 40, or 10 minutes worth instead of an hour. Derp). BUT, I'm not sure how you get 10 M.F. out of 15 R.P. The assembler eats 12 R.P/min to make 4 M.F/min. That's why I broke it down the way I did, that's the MIMIMUM amount necessary to be able to keep up with the demand (R.P. is assembled at 5/min, thus needing 3 assemblers worth to make the 12 R.P. necessary with 3 left over)
EDIT: I should also mention, I forgot to factor in the 24 Iron Rods/min (2 builders at 15/min, 6 left over) needed in the M.F. assembler. Since both R.P. and Iron Rods use 4/5ths of their parts by default, you can toss a Power Shard in the M.F. assembler and crank it up to 125% for 5 parts/min at the cost of increasing MW to 21.4, reducing the wait time to 1.67hrs.
2 Ore Mines digging at a rate of 120 ore/min (5/12 MW each, depending on if normal or pure. Impure makes things more difficult...)
8 Smelters (4MW)
14 Builders (4MW)
4 Assemblers & 1 Power Shard (15/21.4MW)
Total:30 Ore & 5 Modular Frames/min (164.4/178.4MW)
I should point out, all of this isn't TOO unreasonable (after realizing how hard I messed up on required hours) for a game about building efficient factories, and I probably sound like a nitpicking doofus. I'm mostly pointing out how this particular recipe will probably be the thing that stops casual players from digging further into the tree... which is a concern for me, because I don't have the kind of friends that get excited about making efficient factories. Obviously, making the game "more casual" would be upsetting to, well, everyone excited enough to buy this game in early access (and especially the ones excited enough to actively participate in a Q/A forum like this), which is where my slider idea came into play. Not saying it's urgent, but should probably be in the final product.
As far as the recipe itself, I just really wanted to point it out because it seems like not only the biggest resource wall when you reach it, but it's required for a bunch of stuff. I was dreading what I had to make out of it while I was making it, dreading the need for multiple M.F. factories (and the R.P. needed for not only that, but the rest of my stuff) after spending 1-3 hours making, then remaking my first one (settled on remodeling the rest of my factory while that did it's work), dreading the next tier, and dreading doing all this all over again when Satisfactory goes 1.0 and I start a new world from scratch... though that subsided a bit while I was messing around with my "tower" factories with the new conveyor lifts and messing with oil trucks.
Typed more than I though I would again, crap.
TL;DR My logic was slightly flawed in my first post, but I still want to point out a potential need for a re-balance, depending on how many Tiers are in the final product/how many things need Modular Frames... though I will admit I'm possibly being Chicken Little right now.