I have trouble getting through traffic coming from work to race on week nights.
However with a charged LiPo, I have a fresh pack to run for practice as soon as I get there rather than wait for my batteries to charge. Also after I am done with practice, I can bump the battery back up again to race my first qualifier all while I am still charging my NiMh for the second qualifier.
Really! LiPo can make racing convenient and easy.