Walks breaks during race

I did a race this last week with a friend of mine. I was trying to pace her to faster race. I think I managed to speed her up a little, but not a lot. I had her walk up the short steep hills, and occasionally take short walks. She commented afterward that she didn’t think the walk breaks worked for her. Her comment was that it was too hard to start running again, that an object at rest, stays at rest… I like walk breaks. Walking the hills I think saves a lot of energy. I have noticed that when I walk the hills, I am not going that much slower than the people who are running them. But I am using a lot less energy. I am also different muscles than I use when I run, or I am using the same muscles differently. That gives my running muscles a brief rest. All the brief rests add up and let the running muscles work just a little harder.
I use walking breaks during marathons. When I first started running, I would run four minutes, and walk one minute. Whenever the minutes on my watch hit a number divisible by 5, I would walk for one minute. I would also walk the hills. I trained like this for my second marathon. But as I got closer to the marathon, I played with only taking a walk break at the mile markers. This worked out well. I would take a one minute walk break each mile. These gave me a rest, but also served as a goal/reward. I would just run fast for 8 or 9 minutes, then I could walk for a minute. This worked very well.
When I ran my first ultramarathon, I was also training for a marathon. My marathon training schedule called for me to 19 miles at a 9:30 pace. So the solution I came up with was to run 3 minutes, and walk 2 minutes, and of course walk up the hills. This strategy worked quite well, though I ended up walking quite a bit more than I planned due to the extreme terrain of the race.
In my last few races, I have started to decrease the time I walk down to 45 seconds or even 30 seconds every mile. This has worked fairly well. But I will continue to play with walk breaks as my speed and fitness improves. I think most runners short of elite runners could probably benefit from walk breaks.