I changed my mind about giving up. Our Rules and Guidelines states...
" Debate the value of ideas, not the value of the person expressing the ideas."
...so here are the facts as gleaned from many AmSnag searches conducted over a three day period, taking about six hours to gather and another couple of hours to carefully analyze. The idea being debated here is the one that asserts:
". . . you probably won't find any benefits of booking much before the five month mark."
My own assertion is that this idea has no value whatsoever when it is applied to all 32 numbered Amtrak LD trains. This assertion and its corollary (that there are indeed significant benefits in looking/booking beyond the five month mark) are supported by the following facts:
1. There are 32 individually numbered Amtrak trains with sleeping accommodations.
2. Fares are posted by Amtrak for the future 11 month period.
3. As AmSnag (thanks, Paul) can only gather and display fare data from Amtrak in at most 30 day increments, the complete search for Roomette upcharges required 11 X 32 = 352 individual AmSnag searches containing 352 X 30 = 10,560 lines of fare data to scrutinize for days with low bucket Roomettes.
4. Raw data (the number of days low bucket Roomettes were available) from each of these 352 searches showed that each 30 day period had a total number of days when low bucket Roomettes were available on all 32 trains of (in chronological order starting on either 5, 6 or 7 Oct 2018): 177, 434, 321, 646, 690, 290, 284, 313, 347, 347, 374 and 396.
5. The total number of days when low bucket Roomettes were available during this 11 month period was 4,272.
6. The total number of days when low bucket Roomettes were available during the first 5 months of this period was 2,268.
7. The total number of days when low bucket Roomettes were available during the last 6 months of this period was 2,004.
8. The percent of all days when low bucket Roomettes were available during the last 6 months was therefore (100 X 2,004) ÷ 4,272 = 46.9%
CONCLUSION:
The idea that...
". . . you probably won't find any benefits of booking much before the five month mark."
...has no merit because it ignores facts clearly showing that heeding it will lead to overlooking, ignoring or failing to consider about 47% of the days with the best (lowest) available Roomette fares - those during the last 6 months of this period.