Many of us worry as it makes us feel like we are doing something about a problem when in fact we are wasting time being anxious about nothing. Making a judgement call on an aspect of design (could be the frame, outer shell etc) that has an unknown outcome is a decision that affects time and money and we humans naturally don't want to waste either of these precious resources and worry whether we are making the correct decision or not. But if you start to think about any decision you make as being essential to progress, then its easier to make quicker decisions even though the outcome turns out not as expected.