Time limit on summoned items?
 

How long after you go ld or logoff until they poof?

At present, you've got 30 minutes after you log off before they fade.

Now, is this on that particular character, or is it per account?

It's specific to the character that carries the summoned items. You can log all the way out, turn off your computer and take a walk and if you come back before half an hour, the items will still be there. You can play on another character on that account or another but if you're not back on that one in under half an hour, the stuff will be gone. The only workaround is leaving the stuff on a corpose.

This is not classic. Summoned stuff used to poof immediately on logout or linkdeath.