Why didn't the Mexican military follow up on its victory at the Alamo by rapidly crushing the rest of the Texas rebels? Why did General Santa Anna basically sit around doing nothing until the Texans regrouped and routed him at San Jacinto?
Santa Anna was a loser addicted to opium who spent his entire career routing undisciplined beaners who was only given responsibility because he was smart enough to not seize power which would immediately result in his dispossession and probably death. So instead he sort of just "hung out" with vague military authority