Yes. Don't let it get below 1/8 full, for 2 reasons.
1. Over time, a lot of gunk builds up in the bottom of your tank. If you let it run that far down, the fuel pump will suck it up, potentially clogging it's filter and/or clogging a fuel injector. This won't be a cheap repair.
2. If you really really had to get somewhere in an emergency (wife is having her baby, family member was in an auto wreck), wouldn't you feel more confident if you knew gas was in the car?
Chip H.