I agree with 2. I have found that working on the hard parts triggers the realization that something needs to change on my inputs, outputs, or the whole way I am

I agree with 2. I have found that working on the hard parts triggers the realization that something needs to change on my inputs, outputs, or the whole way I am thinking about it much more often than the easy parts do. So I save the easy parts for writing once I know the hard parts are going to work.