Depends.
* This morning I rode directly to the office. The weather was cool and dry. I just wore my office clothes: dress pants, button down shirt, tie. (I keep a blazer at the office for meetings)
* Yesterday was also cool and dry but I took at 20 mile detour as a prework training ride. I wore the full kit. (I brought my office clothes carefully folded in a backpack).
* Tomorrow it will probably rain and I will again take the long way in. I will wear the full kit plus a booties, a windvest, and I'll ride my fendered bike.
It pays to have options.