My husband does a 5 day split. He does not do dead lifts on leg day. Deadlifts are on back day. I'm trying to remember his split, I'm pretty sure he likes to keep them spaced out. I think legs are Mondays and he DLs on Thursdays. If you're doing SLDL, I can see doing them with legs, because the back of the legs gets worked a lot. But, if you're doing "traditional" DLs, you may want to move them to back day, because the lower back is the primary area worked, I believe. Honestly, though, it's more about how do you feel and how it affects your other lifts, so see what works for you. He lifts incredibly heavy, like 2-3 reps a set heavy, so keep that in mind as well.
I recently changed my gym routine. I broke it up so I am focusing heavily on each muscle group once/week as this is what I prefer to do at this time. However, this is the first time I've separated out lower back and legs and I'm not sure where to put deadlifts, or if I should recombine lower back and legs onto the same day. I do many compound movements so there is some overlap of course but I did my best to provide recovery time. Current split goes like this:
I put deadlifts on Thursday but I'm unsure if maybe it should have been on Tuesday. Or should I just put lower back with legs on Thursday and take it off of Tuesday? I can't figure out if the lower back involvement on the deadlifts is sufficient to consider it a lower back exercise.