This may also be a case of moving your heels too much when pushing/pulling hard. I use the same pair of cleats for my fixed gear and SS mtb, both require lots of hard push/pull and I don't have issues accidentally unclipping even though I can feel the slop in the pedal/cleat interface (one thing I dislike about SPDs, the slop).

I stopped riding clipless a few years back, due to knee issues. But, as you mentioned, I never had an accidental unclip. You might be right on that he is letting his heels come around.

If you're going to ride brakeless with SPDs, do not use SH56 cleats! You're highly likely to accidentally clip out at the least opportune time, during a skid.
It's the same reason why you don't see speedplay on the track or ridden by the fixie famous guys.

People's feet do the weirdest of things at the heat of the moment.

Oh I get it now

I didn't know about the "MultiRelease" SPD cleats. Thanks for the heads up, I will be sure to avoid getting by mistake.

These must be marketed to beginners?

Not necessarily but I'm pretty sure LBS's say that plenty though.

It's more of a necessity/ convenience for commuting people on SPDs. Needless to say, none of these makes recommend riding brakeless with any of their products for reasons mentioned above.

Not really just 2 styles. I have a pair of the multi directional and never found them "easy" to get out of. I could see how one would want the single direction but my preference would be a front brake and the multi escapes.

BTW, even if you use the single directions(51s) they will eventually wear down (edges round off due to use) and then they become like the 56s (the only difference really, a strait edge vs beveled edge)

I just looked at my SPD shoes, and the two older pairs have cleats marked SM-SH50, whereas the two newer pairs are marked SM-SH51. They look the same and I've never had any problems with either type. I really don't understand the logic behind the SM-SH56 design, since it seems to completely defeat the concept of full foot retention.

Yep. In my case, I didn't even realize that there were different cleat offerings until I had worn out my first pair, so I had gotten used to them. Apart from maybe one instance, I've never accidentally pulled out of them while riding, and that includes steep hills where I've needed to pull up to keep momentum.

Unintended twisting under duress is definitely one possible cause of popping out, and I suspect another is not having the cleat angled properly from the get-go, so the person is already riding close to one end of their float zone (for lack of a better word), and only a slight movement away from unclipping.

I guess I have inadvertently ridden multi-directionals cleats , because a couple of times I have allowed my cleats to wear to the point they got sloppy , at least on my sandals. But lets face it, if you are wearing sandals, you probably just cruising or touring.

I use brakes, so my concern is not the same as the OP's. I would just rather avoid accidentally clipping out as i hop a curb.

Love it, sharing this with a friend of mine who thinks stopping his fixed gear is like the picture below.

I had the same issue with clipless pedals. Any lateral movement of my foot...BAM! I'd unclip mid-skid...NOT GOOD.

My solution: switched to clips & straps...never looked back.

I've already torn through both ribbon stripped clips and cordura straps with similar holy **** outcomes. To the guy who mentioned cleat alignment, thanks for the level-headed contribution. My cleats are set pigeon-toed a bit to keep the ball of the shoe away from the crank.

Cleat alignment is an adjustment made to set your feet how they naturally orient themselves. Don't force your feet into an uncomfortable position because you will strain and hurt yourself.

But it's the flow man the flow

The beauty of the multi-direction release cleats is that you can wrench your foot out at any time, typically in an emergency or just being a goose by leaning the wrong way at the lights. They have their place in the world, particularly for people who spend a lot of time in traffic.

Simple decision. If your pedals came with them, use them. If you start clipping out inadvertently, and it's not your technique (like the OP), change your cleats, bit like gearing, start with standard and fine tune from there.