Been following Julius Caesar's lead, havn't you? Fortune won't always be on your side, you know.
There is a middle ground you know. You can go for a series of short blitzes to avoid over expanding yourself, but you can still take control of territories in bursts. Make sure you have adequete armies to defend your new found territories should your opponent counter attack with similar tactics. Told from experience, there is no measure of time that will describe how fast you will die should you overexpand yourself. It's akin to digging your own grave.