On a small machine without substantial rigidity you could be better off coming along the side to have a more gentle entry into the cut. However, many face mills have an angled entry anyway and the rpm is normally low, especially without lots of horsepower, so running straight down the middle could be fine and get things done quicker.
Having written that though, I often run down the edge in climb milling mode with both end mills and facemills because this reduces the formation of burrs. Try it both ways and you will see what I mean; if you have the tool leaving the edge of the work under full cut it drags a burr out even when it is new and sharp. When it is dull it can create a terrible ragged burr that is a nuisance to clean off if you are not running along the corners with a chamfering cutter.
An open mind is a virtue...so long as all the common sense has not leaked out.