the 1st one is an overnight layover (land NRT 2pm, leave NRT 10am). As other people say, YMMV

there are luggage lockers(different size lockers and $) AND manned luggage counters (also different costs for sizes). done both, prefer lockers (dont have to wait in line, but you need cash yen or IC card eg suica)

the 2nd one is a sameday layover (land NRT 6am, leave NRT 5pm). I've had a similar length/hour layover for NH->UA, dont need to pickup bags
why bother with hotel? unless you want shower (there are paid shower rooms /capsule hotels available)

have checked in a 2nd bag(carryon) after (extreme) shopping during layover. never tried short-checking bags (no reason to)