I spend my line time reading my kindle --- so I actually enjoy have 15-20 minutes to relax in line.
In addition to using single rider lines where available (and I do wish Disney would expand this to more rides), I adjust my FP strategy when I'm solo. It's so much easier to get same day FP when you are solo (especially when compared to a group, but even when compared to a party of two). I make my FP for as early as I am getting into the park (or starting about an hour after park opening if I'm rope-dropping) and try to get my three done as soon as possible. As soon as I've scanned into the line for my third FP, I'm on the app making a fourth for whatever I can get ASAP. Wash, rinse, repeat. I swear I used >20 FPs last time I was solo in MK. And I did TSMM 3 times via FP last time I was solo at DHS - and that was on a crazy busy (45+ minute wait at GMR) day.