For players who are supporting the team by trucking supplies and building up bases, the rate of "rank points" earned per supply run is far too low. I would estimate it would take about 8 supply runs to go from PVT to CPL ranks. This effort would require well over an hour of game time considering the need to enemy avoid ambushes and deal with the FIA "bots" also.
This is a problem for players who are interested in base building, not only because a LOT of supplies are required, but also because of the "rank to build" requirement they cannot even build protective sandbags or a barracks (which would reduce the supply costs) until they get to CPL.
The rate of "rank points" earned for running supplies is about 1/4 of that for capturing bases. I understand that capturing a base should be rewarded, but the pitiful amount of rank points earned for unloading supplies seems quite unfair in comparison, considering that its quite a mundane and thankless task that benefits the whole team and only a few players are normally willing to do it, or understand that its important or even know how to do it (noobs take sometime to get an understanding of the Conflict game mechanics).