After my training for and running a HM recently using run/walk, I decided that I would "reset" my non-stop running by following a series of 3 HR plans by Roy Benson. This basically running at the top end of my Zone 2- 70%( around 132 BPM for me @ around 8 mins per K on the flat) for 3 days per week plus one day doing HR fartleks - running up to 75% 138 BPM and walking back down to 60% for up to 5K on one day per week. It started out at a weekly total of 2hours 25 mins - have worked up to 2Hours 45 over the past 4 weeks and will go to 3 hours 30 mins per week ( fater I reach 3 hours) soon with the addition of a fifth day of running.
After that I will maintain the 3hours 30 mins per week of volume but slowly increase the intensity of some of the days - up to 90% of HR max. Faster harder fartleks day and a harder parkrun day ( which I am currently doing easy)
I must say that I found the slow and easy non-stop running to be quite hard for the first few weeks - but am now "adjusting" to it. My longruns only go to an hour long - I may increase that to 1.5 hours and see how well I handle the harder running days and increased volume. However if I ever do do another HM, it will be run/walk again. O rmaybe I might just replace a non-stop longrun sometime and do a longer run/walk for a change of pace.