Well, my general gave me shitload of land and money, and emperor have me nothing, so which way to the Rubicon?

Explanation: Alexander’s army famously mutinied near modern-day India because they were tired of campaigning and wanted to go home and see their families again. Macedonian soldiery were professionals, but in a system that operated under traditional warlord’s logic - you go home when the campaigns end.

Rome, on the other hand, eventually developed a professional system in which troops were constantly being rotated in and out of service, with a (more or less) definite start and end to one’s term of service. 20-25 years is a lot, but it’s also certain - the next campaign isn’t going to take you away from your home province indefinitely. As such, with the older, more likely to be exhausted soldiery being regularly dismissed to a pleasant (and paid) retirement, and the newer, hungry-for-loot-and-glory troops being constantly brought in, even during campaigning, the Roman Legions maintained a high level of enthusiasm for going on new campaigns, in most cases.

Unfortunately, sometimes this led to the Legions deciding in times of calm that THEIR general would be a better (read: more enriching) Emperor than whoever had the office at the time! Pros and cons!