When you did night sleep training, did your LO's naps improve as well?

I am looking into sleep training or ways to teach my LO to self soothe. He is unable to self soothe AT ALL which makes it really hard to take him anywhere. He will only fall asleep in MY arms or my husband, no one else. He can't fall asleep in his stroller or carseat or anywhere else unless it is our arms. I obviously will start with night sleep, but did you have to sleep train for naps as well or did that come on it's own from the skills your LO learned at night? My LO is 5 months now, I am waiting AT LEAST until 6 months to try anything. Any tips or suggestions is greatly appreciated.