I have to chuckle every time I read some authority state that no one, not even the pros actually pulls up on the pedals. If I am fit and have been riding, I regularly pull my slotted cleats off my pedals if I don't pull the straps tight. I am so used to the clicking from the transition from lifting/floating over the pedals to the aluminum cleat coming down on the pedal after 12:00 that I am no longer aware of it but it never goes away.
Fun thing I did a couple of weeks ago on my best fix gear. Went for a ride up to and along Bald Peak Road on my fix gear. Brought 4 cogs and the tools. 23 and 12 for the hills. Rode the 23 to the first high point then swapped to the 12 (42 in front.) After the moderate descent on the summit road, I decided to simply muscle the big gear over the next rise. Probably 150: vertical and not more than maybe 7% but in a 95" gear, that becomes real. I simply settled into a full body push-pull. Used inertia to carry me through 12:00/6:00. It was fun! (and completely impossible without full foot retention).
A benefit to pedals with retention is that many are narrow with excellent ground clearance. I hate having to take time out and coast for routine corners,