Back at Selly Oak, I'm reminded of one of the more valuable bits of advice I've gleaned from model railway magazines.
In an article on building an N gauge display layout with some Z gauge forced perspective was the statement that when building something, if what you make isn't right - discard it. If you don't, the less than perfect item will always niggle you no matter how good the rest of the model.
I had a bit of a bad day when attempting to finish the pavements.
Attempt 1 - I marked out the flagstones incorrectly and ended up with them twice as long as they should be. The marks should be every 6mm, not 12. Then when you scribe every other length so the slabs are correctly staggered they line up.
Attempt 2 - Then I realised that I was also marking them out at 90 degrees to the direction they should run to match the rest of the model.
Fortunately, this is only a small piece of pavement, so it wasn't too painful to make this bit three times. A bit annoying though....