seriously, in most of his fights, it is never damage that gets him, but fatigue(in fact, he almost never takes anything more than a glancing blow). now, we all know what soldier pills do: they make you able to fight ofr 3 days, and replenish your chakra. popping a soldier pill would save shikamaru quite often. some examples: had he had one during the chunin exams, he could have held those sound nin for quite a while during the tayuya fight, it was his lack of chakra that allowed her to eventually gain the upper hand, had he had a soldier pill, he could have replensihed his chakra and may have even been able to finish the job(choke her out). during the latest fight, if he had a soldier pill with him he could just pop it and be ready to fight at 100% again agaisnt hidan and kakuzu(team asuma needs all the help they can get, he also may have been able to save asuma from hidans new curse) add to this, that his best friend choji's family actually MAKES pills such as these, then there is no reason he does not carry a supply with him to help him in his fights.