For warp singles that must be very strong, I relax mill-prepped fiber with a gentle breath of steam. I lay the commercial top or roving on a wire rack and use a garment steamer to gently steam top and bottom. Then, I spin my threads, and block the threads with steam. The steam blocking of threads is easy - I wind off onto a reel, steam with my garment steamer, then wind the thread onto bobbins that fit onto my bobbin rack. I find the double steaming to be faster and easier than sizing or massively increasing inserted twist. Thus, my final threads only have a firm twist factor.
Looking again at AA, BBB, pg 240, we see that he talks about spinning 5,400 ypp at between 12 and 16 tpi on a great wheel. Since the great wheels with the spinning technique AA discusses for GW's use, produce woolen yarn, and 12 to 16 tpi is way more twist than is needed for knitting yarns; we have to assume this is for weaving. And in fact, woolen yarn spun at 5,400 ypp and 15 tpi, then steam blocked works very well for warp. It is very possible to produce "woolen" cloth using woolen singles for both warp and weft. The woolen singles "bed" to form a unique fabric. Then, when when the cloth is milled or waulked (see for example https://en.wikipedia.org/wiki/Waulking_song) one has a very warm, durable fabric.
Some may assert that the commercial top, straight from the "bump", produces a more perfect worsted thread. I am not ready to argue this. However, folks were spinning true worsted threads of very high quality, long before mills were straightening fiber with steam. Then, those handspun threads were hand woven in to fine cloth. I think commercial top relaxed with a breath of steam is more like the traditional fiber prep, and for hand spinning, the relaxed (crimpy) fiber produces a stronger, more elastic thread. That is my story until someone shows me different (or, buys me another beer.)
AA suggests on pg 241, that a traditional great wheel (without an accelerator can produce 255 yards of 5.3 tpi woolen thread per hour. On the other hand, the AA flier/ with DRS and an accelerator will easily produce 600 yards per hour at 9 tpi of either worsted or woolen singles. In fact, one can easily spin 600 yards per hour of good 5,200 ypp woolen singles with a single drive bobbin lead flyer/bobbin assembly (German Tension/ Irish Tension). If you want to weave without the hassle of spinning a worsted warp, weave woolen cloth. If you want to spin a fine worsted warp at a reasonable pace, use differential rotation speed (DRS).
It is Spinzilla! Spin at "warp" speed.