Reality checks are meant to be done regularly. Not at any given time and in a large amount but just periodically throughout the day, every day. That way, they will become a habit and follow through into a dream.

So, if a common dream sign for you is people from your old town, then when you do come across them, by seeing their photos, hearing them and so on, then you should most definitely reality check. Aside from that though, it's a good idea to get reality checking into a regular habit. Not too annoying, that will only backfire, but periodically throughout the day, whenever it comes to mind.