Yep, and to say it once again, no prep work survives first contact with the players anyway. It's getting back on the preplanned track that feels like-- no, wait-- IS railroading. But every so often they do what you are somewhat ready for, and sometimes that makes you look good. :)

Generally if things work at all, they work out better than I planned, but of course nothing like the story I envisioned. So I never get my heart set on anything as a GM and it's all good.