Ken,
Wow, did you ever get a ton of responses to this one! I read them and it made me want to build my table all over again. I am a first time builder and the one thing that definitely stuck out in my mind about what I did was that the initial setup (16' long x 4' wide surface of 1/2" plywood with three sawhorses and 2 x 4s underneath) was not enough room to do epoxy all my initial scarfs at once. Some of that was probably due to inexperience. I also am building outdoors so I had no other place to epoxy scarfed wood. A garage or shop floor would have been great and I never would have needed the 4' width.
Once the wood was scarfed and glued I began stitching and the 4' table was too wide. I struggled through it and set aside the project for 3 months. When I resumed work I cut my table surface to 2' and it's been that way ever since. Shortly I will be glassing the boat and will be switching to sawhorses only.

So 2' table width maximum is a great rule to go by such as others have already mentioned.

Have fun,

Tony

PS--I have learned so much from answers to other peoples questions that I rarely have to post my own. Thanks.