Good listen Well worth a listen, goes into the detail of various FTP testing protocols, and the positives and negatives of each. There is another thread on here FTP Test that also is well worth reading through.
Personally, I find the ramp test a complete lottery, and rarely does it reflect where my threshold lies, it often gives me a figure that I then exceed in a 25m TT by a considerable margin or even in workouts on the trainer. So much so I no longer use it as not only is it inaccurate for me, it isn’t really a relevant workout for me. No doubt it suits some, but worth listening/reading up on other methods and trying a few to find one that suits you. Personally if your target requires sustained power such as time trials I can’t see why you wouldn’t want to test longer, it’s the nature of most events from Gran Fondos to road racing, so why cut corners when it comes to testing?