I use plain platform pedals, toe clip and strap pedals, and Look system clipless on my various bikes. I have no problem transitioning from one to the other.

I use the Looks with cycling shoes for the road bike where I might be riding for hours. The toe clip and strap pedals are for the commuter, for my typically 1/2 hour ride (though I can make it much longer when I feel like it), and allows me to do errands on the way. The short haul "bopper" folding bike has plain pedals, and gets used for short hauls and errands in town. I consider it's range to be about 10 miles max.

My point is that there are no rules and you should use whatever pedals you feel meet your needs, or like I do, all three types depending on the situation.