I've always been afraid about starting all over for some reason. I think the biggest of them is the fact that I see my peers make so much progress in the same situations and with similar opportunities as myself, that I become somewhat jealous of my inability to produce the kind of results that I see around me.
Of course some factors are due to circumstances beyond my control,but I think most of those results are well within the realm of possibility and action, leaving me feeling like I should have done certain things differently. Realising the need for a reset isn't fun when others are making significant strides of progress everyday. It really bites to have to realize what could have been over the reality of no progress made.
That said, starting all over in the face of significant issues with the original plan is a both a luxury and necessity for forward movement. It is a luxury in the sense that not everyone can start over. Some people are deep into a particular mess they may find themselves in and chose to rather dig further in than try to come out of it. It also isn't everyone that realizes the need for reset when it becomes necessary.
Of course choosing to rebuild is just as uncertain as it sounds. It is also filled with a lot of self doubt and expressions, but it provides a bigger avenue for true progress to be made. As always, we see what the future holds.