This exact thing happened to me while playing Forest. I couldn't get past chapter 6 or so because there was a choice that seemed to me like it should be essential to the story. Turns out picking it caused an automatic dead-end, but only at the end of the chapter so you didn't know where you screwed up.
I usually finish them alone, unless I absolutely can't get the route I want. I had to use one to find Rin's route in Katawa Shoujo for instance, and I had to use one to find Natsumi's route in Sharin no Kuni
Just finished it, it's a good game!
More recently finished Sharin no Kuni, which is an equally excellent game.
Now I'm playing Kyoudai ~Futari~. A futanari romance game.
There was a huge lesbian on the last forum I went to who played lots of yuri games. She also seemed to have a huge obsession with Lightning Warrior Raidy.