Just as “ontheball” noted, the development of running A’s and similar drills - whether for power-speed or strength-endurance - was out of necessity due to inclement weather conditions. Mach’s drills were appropriate replacements for longer runs and sprints due to the snowy and cold weather in Poland. When they came out of winter training, Mach’s runners did very well on the track due to the use of such drills.
Your decision to use these drills will be based on what you are able to do in your given circumstances. Can you run outdoors over longer distances to build strength endurance? If so, perhaps your use of running A’s is limited to technical drilling and some minor supplementary strength endurance work. In Charlie’s case, they were stuck indoors for late fall and all of winter in Toronto. Hence, use of these drills was appropriate given the circumstances, much like his short- to long approach to speed work.
It should be noted that use of the Strength Endurance drills can be taken out of context and create lots of problems for athletes. I knew of coaches in Canada in the 1980’s that would extrapolate Gerard’s materials and have athletes perform a full 400m of running A’s around the track in multiple sets.