For you that are starting to get experienced with freeciv, and know how to largepox and celebrate your cities to size 20, there is a lot to gain by using govenors. Govenors save time. And in online gaming, time is the asset.
Before I celebrate, I usually micromanage my cities. Micromanagement take time, but early the game and the cities are not too complex. Later in game, when I do multipple traderoutes pr turn, or celebrate all my cities, there is not enough time to micromanege all cities every turn. Instead I use govenors. For this purpose I have custom made govenors that maximize base-trade in my cities by using tiles high on trade, when making multipple traderoutes pr turn. And I have custom made govenors I use when celebrating that optimize economics (gold pr turn) or science (bulbs pr turn).
A trick I often use is to change govenors to max trade just after the turn change (TC) before I accept any new traderoutes. When all traderoutes are done, I change back to preferred gaovenors that I want during TC. This imply that I cahnge govenors twice a turn until either (1) all traderoutes are done, or (2) cities are using all available tiles. This kind of frenetic govenor-use require that you are accustomed to use City-tab (F4) when managing your cities, and that you name your cities in a meaningful way that make it easy to sort all your cities before changing govenors.
I hope all you pro players post some of your tiricks.