He even highly recommended for King Michael to pay them, even if it is as low as 50 Gold Coins.
But with other expenses covered such as paying Spearfishermen, if he paid 100 Soldiers, it would mean that Gaster Kingdom will have an economic collapse. A wall can't be pushed with one's head after all.(Unless you are Kaleem).
So until Gaster Kingdom reached a stronger Economical standard, these Guards need to work for food, shelter and self improvement.
After completing their hour long Stabbing Lesson, they would need to run 3 more laps after a short break of course. Repeating the same thing over and over would be hard even if one just jumped over and over, so they need time to relax.
You would ask why Woldemir puts so much importance into running laps rather than learning more and more fighting techniques.
Well running has many benefits when it comes to Swordsmanship.