At least that is my thinking.

If I had a soil with a 7 CEC I would use lots of applications during the year. Probably would split the potash into spring and fall. The phosphate put it out in the spring OR fall your choice. and 50 lbs of nitrogen for each expected, probable, usual, desired grass hay yield for the next cutting.
Split the potash in Spring & Fall for winter survival and summer survival.
The phosphate being even less mobile I would put it out when it is convenient.

If I had a soil with a 20 CEC I would consider applying all my fertilizer for the year sometime in the Fall.

Amounts of P & K would depend. With these soils I would apply enough to bring the soil test indexes up to your desired. That is 15 to 25 lbs of P₂O₅ & 5 or so lbs of K₂O to increase the soil test indexes by one (1) ppm, plus at least half the amounts expected to be removed by the hay crop.

If you had soils that are in the 40 to 60 CEC values I would and do make adjustments. Roughly I multiply the CEC value by 8 & 10 = desired K ppm, and fertilize potash to be in that range. I would figure half the N applied this year is available to the hay crop and half the accumulated ie residual N is also available to the hay crop. Soil testing is of little value for nitrogen in a real high CEC soil.

If you had a calcareous soil with an 8 pH I would add 50 to 70 lbs of P₂O₅ to change the soil test by one ppm.

Just remember it is your farm, and your income. The Labs and Soils Departments have only an academic interest in your productivity. It will be fully up to you to make adjustments for your soil, climate, management style, equipment, and regulatory burden.