Stockpiling resources in order to build something is never interesting. Never. Not even a little. In games like Pharaoh and Children of the Nile, the essential element of the game is the player waiting for resources to stockpile, on many occasions for a far longer period than the total time necessary to set up the infrastructure necessary to acquire said resources. In other games, such as Sins of a Solar Empire, players specifically manipulate the system of resource stockpiling in order to avoid penalties from increased mobilization -- one player acts as the "pocket" of another, with the pocket player producing without using, and the combat player using without producing. So, in addition to the tedium of waiting for resource accumulation, the stockpiling method also lends itself to exploitation. Finally, and this is key, a stockpiling system gives the player significant and unwarranted independence from their means of acquisition by allowing them to stockpile a sufficient quantity that the standard opportunity cost assessment of investments that would usually apply falls to the wayside. This is especially apparent in the late game of many real time strategy games, where players can afford to utilize all their structures simultaneously without significantly impacting their reserves.

Grand Ages of the Roman Empire, on the other hand, uses a flow resource model. In this system, every resource producing building immediately produces to its current capacity as soon as it is activated -- and that capacity can be increased through research and the assignation of more qualified personnel. These flow resources do not stockpile or otherwise accumulate, although additional buildings, once onlined, are summed to increase the total flow. While being built, units and buildings consume a portion of the flow temporarily, but cease to do so -- excepting an upkeep fee, in all cases lower than the consumption required for initial creation -- once construction is complete. 

This flow concept of resources allows for deployment of structures once a sufficient infrastructure is created to maintain them, rather than forcing the player to wait a mostly arbitrary amount of time for resource accumulation to complete. It rewards the player for map control and an aggressive, raiding play style without compromising the ability of more passive players to develop. Furthermore, upkeep costs function in a more organic manner than the now traditional method of map control penalization -- decreasing the average income from all sources by an arbitrary percentage as the number of units increases, as in Sins of a Solar Empire and Warcraft 3 -- allowing the player a finer level of control over the level of penalization over a wider range of resource types. Finally, it rewards careful placement of resource acquisition structures -- careful locating of the aforementioned structures increases the average marginal benefit without increasing the average marginal cost. 

Therefore I advocate that, where appropriate, a flow, rather than a stockpile, method of resource acquisition be used.