From: Madrid, Spain
If you're on point short of achieving a skill then there was a chance (don't remember what percentage) of getting the last beacon and obtaining the new research level. That same chance also applies when you have the invested the total amount, you will notice it because you will start the next level with one beacon already.
I recomend investing in R&D, specially with the russians they're way behind of german war levels. Having advantage in R&D can tilt a game in your favor.
About how much you need to invest in R&D, units and sigint you have to find your own balance, when you start pbem it will be a lot harder since every human opponent can display a different strategy.
GG's AWD, GG's WBTS, GG's WitE Beta Tester
Beta Tester: Panzer Corps, Time of Fury, CtGW, DC CB, DC3 Barbarossa, SC WWII WiE, SC WWII WaW, SC WWI