It's an interesting discussion that Paul started. His photos are always inspiring and I can see his point in using realistic figures for the "beauty" shots. I don't necessarily agree that it's important that we strive for realism so that people who view our photos see them as modeling rather than toys. Playing is OK and we shouldn't let the kids have all the fun. I sometimes get the impression that some of the model RR community, in all scales, are critical of non-realistic modeling because they are embarrassed to be perceived as just playing with trains. There were a number of articles a few years back in Garden Railways Magazine about "2nd generation garden railroading" that implied that we would eventually all grow up and have a precise theme, scale and method of operating our garden railways. I found this to be more than a little bit pretentious. According to those authors my railway should have a legitimate "Reason for being". Well mine does - it's purpose is to make me smile - and if that means having a dragon in the castle or running trains round and round while I have a pint then I'm a happy guy.
I do try to make some attempt to create a realistic atmosphere in some of the areas of my layout. The plants in the garden are never going to be exact scale replicas of real one's but I'm content if the colour and texture add to the scene. It's important to me that the overall effect is still a garden.
If the entire layout were super detailled it would look to me like an indoor layout transplanted outside. Sort of like a big green wedding cake. So what I try to do is have just a few places, like the stations, that are as realistic as I can make them. These become the backdrops for most of my photographs.
In other places I have some fun. The only reason that there are no Playmobile figures here is that Smog the dragon ate them before I could get the camera out
So it's possible to have multiple railways in one garden. I remember seeing a garden railway in a magazine that had European buildings at one end, North American at the other and no scenery at all in the middle. Brilliant! You could run whatever you wanted and always have an appropriate background.
Finally, I gave up worrying about scale a long time ago
Have fun and keep the good ideas coming.