Babywise?

When Jack was a baby I often felt like I had no idea what I was doing, especially regarding sleep. This lead me to read books in an effort to "educate" myself. Reading these books, in turn, made me crazy. They always left me feeling as though I had already screwed up and the damage was done. So after a lot of distress I did away with all the books and went back to figuring things out on my own. Looking back I can see that Jack turned out fine, turns out I hadn't ruined him. Though I wouldn't say we went about his sleeping in the best way. Now here I am again, feeling like I have no idea what I'm doing. I'm exhausted and really need my babies to sleep longer and night and nap better during the day. Although, I've been quite stubborn about reading books, I decided to read Babywise, based on the advice I'd gotten from others. It surprised me. Turns out I was already doing a lot of what it said and turns out it wasn't the super strict "schedule" I'd thought it was endorsing. It still made me feel like a failure, but perhaps that's not so much the book's fault as it is  my own lack of confidence. I think I got some useful information out of it, but I'm still left with a lot of questions. For instance, Babywise says put your baby down for a nap while they are awake. They might cry, but they'll learn to self sooth. My question is, how long might they cry. Seems like everything I read says "oh they might cry for 15 minutes, maybe a little longer". Ha! My kids can cry for 30-45 minutes, probably longer if I'd let them. They scream and carry on with no sign of winding down and falling asleep. So then if you really go for it and let them cry but they cry until they're supposed to eat again then what? And what about those babies that don't take long naps. When I read that they should nap for 1.5 -2 hours I laugh. Jack napped for 30 minutes. I don't recall all the details, but I know I tried to make that longer and it was hard and took a lot more time to teach him than 3-5 days or even 2 weeks. So if I have one baby who naps for 30 minutes and one baby who naps for 1.5 hours.....what do you do? How do you get that first baby to sleep longer? I've decided their needs to be a Babywise hotline...or some sort of hotline to call when situations arise and you don't know what you should do. It's so hard to balance what the books say your baby should be doing and what the books say you should be doing, with what your baby actually does and with what actually works for your family. Cause I do not have textbook babies.