No Doubt folding the plans is the least expensive way to go, however not the best quality for the end user.
As a designer who has both sent and received drawings for almost 40 years, I understand and commiserate with everybody regarding postage and shipping rates overall.
The other year I received a couple sets of rolled up plans (from a well known provider) that were then purposefully rolled then folded in half to fit a 24" tube for lower shipping cost, and I was utterly shocked that anyone would do that to a beautiful set of plans.
I called the service and respectfully shared my professional thoughts (I was kind of incredulous, but wanted to solve what I thought was a problem) and to his credit he went out of his way to buy the larger shipping tubes to ensure the higher quality. He also mentioned that other customers didn't mind the folder/rolled up plans.
In the end, the buyer of the plans has two choices, fold 'em and save money, or pay the expense for full rolled up plans.
Note: The folded plans can be ironed out to smooth out the wrinkles carefully. I once received a 1/4 scale set of Fokker DVII plans that were crushed in a USPS triangle tube, which badly wrinkled the plans. I reversed rolled them loosely for a couple of weeks to smooth them out. Ya do whatcha gotta do : - )
Take care everybody, Piano man