When building user interfaces in apps I generally go through two or three phases. First is the building phase where I put all the design elements together and lay them out close to the design but not precisely. During this phase I’m concentrating on functionality and making things work rights so the design isn’t the priority. I also find that after working on the functionality for 15 hours over two days that I don’t have the energy or perspective to get the design right. My perspective I mean that I’m too close to it from looking at it so long and I wouldn’t know whether it was right or wrong.
The next phase is the polish phase. I approach the design days later, after going through the build phase on the rest of the screens of the app, with fresh eyes and I can see what is and isn’t working. Usually this phase only includes minor tweaks of colors, placement, and size.
The last phase is the test phase, where I look at the design on various screen sizes to ensure everything still looks good and I make tweaks where necessary.