Volksgrenadiers got 6 weeks training in WW2.
Sure. But the Volksgrenadiers were late-WW2 units, created.. I won't say in a panic, but after significant losses. And they weren't tasked with taking the enemy on in melee combat, which is the basic norm of fighting in the FR where you've set this.
Unless you are setting up for Mary Gentle's book, Grunts, (which answers the question, "What if the orcs got M-16s and AK-47s?"), WWII analogies are not going to match the reality you're considering.
6 weeks of physical training can do a lot as long as someone isn't drastically unfit.
I don't think it a stretch to think that most of the middle-aged folks hanging around on D&D message boards haven't hiked 10+ miles a day multiple days in a row for, well, years.