Length of Personal Story segments

Maybe somebody has already brought this up but I couldn't find it. I'm not the youngest player and some of these things can take me a couple of hours. I know, I know - get in a party, get your guild mates to help, etc., etc. It's just easier said than done. I run out of steam and would love to be able to call it a day/night in maybe an hour without having to start all over again. Just a suggestion for players with less stamina such as myself - shorter story segments.