Should you look at local competitors before designing?

Yes, so you do not repeat the colour, the icon and the type already on the same street. Not to copy whoever bills the most: you look in order to separate, not to look like their branch. Walk the block, or search your trade and your area, and note sign colour and icon. Three lookalikes are enough to know what to avoid. On a Madrid street three clinics open in blue with a generic cross. The patient books the one they did not mean. A note of what already occupies the street and a mark that does not fall into that gap. The palette is chosen against that note, not against a trend.