Exceln,
I used to have the same opinion as you until I had discussions with a number of FAA designated examiners and POIs. As a check airman and director of operations for the last 10 years, I have become acquainted with the FAA 8400 inspector's manual. The grace period provision is actually referred to as a 3 month eligibility period in the 8400 manual. If you do not complete the required checking the during the month due, month early or month late, you may still serve in revenue service but are required to complete a requal check thereafter.
I have pasted the paragraph from 8400 and also a link.
Hope this helps,
Corp Pilot
B.
Eligibility Period. The eligibility period is a 3-month
period comprised of the calendar month before the month
in which training is due, the month in which training is
due, and the calendar month after the month in which
training is due. In both Part 121 and Part 135 operations,
required recurrent training or checking that is completed
any time during the eligibility period is considered to have
been completed during the month in which training is due.
A crewmember who has not completed all recurrent
training or checking requirements in the month due may be
scheduled and may serve in revenue service during the
remainder of the eligibility period, but not thereafter. A
flight crewmember who fails to complete all required
training and qualification modules within the eligibility
period must complete requalification training before serving
in revenue operations.
www.faa.gov/library/manuals/examiners_inspectors/8400/media/volume3/3_002_10.pdf -