Or do you have to take another pair of shoes everywhere with you? Is there any particular shoe/pedal arangement that is good for both cycling and walking?
There's "walking" and there's "going for a walk"!
Most cycling shoes with external cleats are hopeless-to-lethal for any kind of walking. I like my Sidi shoes, and Look pedal system, but only if I stay on the bike. As soon as I start wandering about at cafe stops, I'm sliding about all over the place and wearing the cleats down.
For that reason, I switched to the SPD system. SPD shoes are fine for walking short distances in; the kind of walking that you do on a bike ride! They are not the kind of thing that you want to go for a decent walk in. A few hundred yards on paving slabs or tarmac yes - over rocks on a mountain ridge, or wet stepping stones in a river - no!
So any type of cycling shoe for cycle rides, SPD shoes for cycle rides and short walks away from the bike, SPDs plus walking boots/shoes for cycle rides mixed with long walks away from the bike.