Nuts Connection HND?
 

I'm arriving HND 23:00 SQ from SIN & Departing HND on DL to LAX 00:30. I'm assuming both flights will be located in the same (I) terminal. This doesn't sound too crazy does it? I do have 1 checked bag and these are 2 separate tickets. Reason-Booked with miles!

Apparently, 45 mins is legal for international to international connections at HND. The airlines should be able to tell you if they will interline your luggage... Even so, I wouldn't risk 90 minute connection on separate PNRs. If you're delayed by an hour at SIN, you could be SOL. I don't think it's worth the risk. YMMV.

EDIT: jerry a. laska has posted the legal connection time for SQ to DL connection from Expert Flyer in his post below.

If this was booked on one PNR, I wouldn't have the slightest hesitation about doing this; HND is an incredibly efficient airport and I'd doubt that you'd even need 30 minutes. However, as jib71 notes, with the risk of separate PNRs and potentially having to recheck luggage if no interline agreement is in place, I wouldn't be comfortable with what you propose.

With no checked bags, 15 minutes is sufficient assuming flights are on time.

With checked bags, very high probability that they will interline, in which case 45 minutes is sufficient.

If they don't interline, you could do it in 60 but it might be a little tight. 90 minutes is more than enough.

OP should certainly verify this in advance with the airline. My gut tells me that SQ and HND are probably happy to interline bags. But I recently read that DL is no longer interlining baggage for customers with split tickets.

Legal connection times:
Results from ExpertFlyer.com