I would say it all evolves down to your personal preference. Many variables involved; space available, height if you sit or stand, what will you use it for, and so on. Right now my router table is my main work table, it is about 18"X24" or so, I sit while using it. This has worked well for me, but I am planning on some work changes, so am thinking seriously of extending the left side about 2' maybe, possibly a bit more. For me it will work fine, for most others here doubt they would like it much. I will have to make a glue up jig too, probably about 12"X18" or so, don't know if I will have to make a stand or shelf to put it on or not. I always just think about what I want, decide on the size, and make it.
Plans? Plans? Don' need no steenkin' plans. Plans are someone else's idea of what you need, so I seldom follow plans, just use them for ideas, and make whatever the way I actually need it. Works for me.