On a stationary bike in a gym?- sure, use whatever shoe and amount of retention you want(none, straps, spd).
On a 10mi family ride for ice cream?- sure, use whatever shoe and amount of retention you want(none, straps, spd).
On an exercise/enthusiast/training ride?- Im clipping in every time. Hills suck even in the best of conditions, so why make them more difficult with platform pedals?
Ive always considered myself quite athletic with good balance, but maybe this is a time where I realize my balance isnt great because I see benefit in spd when standing and producing torque/swaying up a hill. Regardless, its a noticeable difference.