New Run/Walk Strategy Developing

I was glancing out the window of my nearby Dunkin' Donuts here in far-northern Gainesville (see above pic), where I do much of my writing and studying, I'm contemplating a "sea change" regarding my future running and speed walking as I continue to plod on through the years. On my neighborhood run/walk combination training outings the last few months, I've grown accustomed to mixing them up.  Today I covered the 4.1-mile course by spending most of the time speed-walking with short, period intervals of easy-paced running.  I feel this may be the pattern for future races as well...especially the long distances ones of 10K (6.2 miles) and longer.  Speed-walk for six minutes and then run for four...and keep repeating the process until the race (or workout) is over.  I think this is a feasible training strategy for a future marathon in which I'm pushing to finish faster than six hours...there's one coming up in January. Today's workout was typical summertime discomfort, with an annoying combination of high temperature and humidity.  When conditions get cooler and dryer, it should be more workable to extend my training to longer distances and see how my body reacts to it all.  What I want is a viable level of fitness with which I can confidently enter any "classic" long distance event (10K through marathon length) and finish at a reasonable time...or in the case of the marathon...before they close down the course and stop timing entrants.  The elitists at the Florida Track Club have already stated that six hours is the deadline for finishing their upcoming marathon, after which runners are on their own and will not be furnished with posted finishing times.  A shoddy attitude, I think, considering the money laid out to enter the race, but obstinate, disagreeable people are everywhere and I would be better served focusing on my own attitude and behavior in response.  Let's try out this new alternation of walking and running and see where it gets me, elitists or not.  On the surface, it seems to make sense.  With this new structure I'm walking more than half the time while I'm running more than half the distance...