RoughRomanMemes

Explanation: Not all garrison assignments are made equal! While some provinces had no permanent standing Legion assigned (instead being policed by smaller numbers of Legion detachments and auxiliaries), several larger provinces had just one, as a 'just-in-case' measure.

Provinces like Egypt were a great posting - corruption was rampant, most people weren't Roman citizens (and thus had less 'sway' when accusing a soldier of wrongdoing), and a truly ludicrous amount of wealth passed through the province, and was taxed by the Legions. Not only that, but anything more dangerous than minor banditry was extremely rare! Peak posting for a comfortable career! Stuff your pockets with bribes, chisel some dates from the local orchards, harass the locals - life is good!

Provinces like Tarraconesis were generally garrisoned only as a precautionary measure - while Spain was, at one point, dangerous, by the time of the Empire, it was a nice, quiet, prosperous province. Plenty of time to chat with the locals, make economic connections, plan for retirement - pick out a nice plot at a low cost, get to know the land, and find a prosperous citizen farmer desperate to marry off his daughter!

... provinces like Germania Superior, on the other hand, were the frontier, and not just in the literal sense. Some frontier provinces, like Africa and Egypt, were fairly quiet - Britannia was miserable in terms of weather, but generally suffered no more than minor raids from Scotland. Germania Superior was one of the real shit postings, where Roman legionaries were sent to be ground down in a constant dance of invasion and counter-invasion, each side attempting to convince the other by force that sending another raid was a bad idea and would lead to CONSEQUENCES (for some reason, both sides always seemed to consider it worth the trouble anyway). There were no quiet decades in Germania; there probably weren't even quiet years.

If you were posted in Germania, you could 'look forward' to constant, brutal warfare against the local tribes, who aren't even populated or rich enough to be worth the loot, in a cold and hostile environment, where starvation in the uncultivated Germanic woods is as likely as ambush, and even behind the borders, still surrounded by civilians who may be more enemy than Roman subject.

Provinces on the borders of the Persian Empire were a crapshoot - it could be quiet for literal decades, and then it could turn into a horrific meat grinder for decades. All depends on dynastic politics!