Our Chassis, who is almost 13 years old, is the scourge of the neighbourhood. She is a scrawny little thing, no weight to her at all but she will take anyone on. She and Kirsty, the garden cat fight quite a lot. When she deigns to come indoors, if any of our cats pass anywhere near her, she gives them a clip even though they are all twice her size. Kirsty has started shooing her kittens away now that they are nearly 5 months old so we are going to get them 'fixed' as soon as possible while they are still accessible.
It's a great pity the right of free speech isn't based on the obligation to say something sensible.
We have had a few cats wander off over the years and, as you all say, it is the not knowing that gets you. We had one cat, Max, wander off some years ago. He was a large, un-neutered male and we always assumed he was following a female scent and either got lost or just decided to stay wherever he ended up! Over the next couple of years or so we kept spotting kittens, many streets away, with very familiar markings (his were quite distinctive!). He had obviously been busy!!
It wasn't Shadow after all. The cat turned up again at the ladies house and I asked her for a clearer photo of her face. Shadow has a white moustache. In the new photo the lady took, it only had half a moustache. That was all I could see in the older photo but not it was clear, it was not her. I am disappointed but at least I know that wasn't her.
Maybe one day she will return. As others have said, it's the not knowing.