IMO no Spell or Potion should last until Long Rest. Non combat Spells at best until Short Rest, everything else - 100 turns max.
As to Ability Score changing magic items - well, in BG1 one made a beeline for the 18 (IIRC) DEX Gloves :P. But there was no respeccing then (and we went to school uphill BOTH ways too!).
