Hueyracer - AMC FCL.740 actually says:
"The amount of refresher training needed should be determined on a case-by-case basis by the ATO".
The elapsed timescales quoted are for consideration only i.e. they are not mandatory, and:
"Once the ATO has determined the needs of the applicant, it should develop an individual training programme that should be based on the initial training for the issue of the rating and focus on the aspects where the applicant has shown the greatest needs".