It does remind me of a good lesson I learned about loco repair. Many of my friends that do installs and repairs will recount horror stories about the locomotive that could not be fixed, i.e. it's fixed, it's tested, but as soon as it arrives at the customer's it does not work right.
I remember in particular a Z scale big boy (4-8-8-4)... working on Z scale is an effort enough, a single hair can make a loco not run right. This loco had been back and forth several times. My friend had a set of simple loops just like at Piko.
Well, he always put the loco on the track the same way, yes he did run it forwards and backwards, but the loco was ALWAYS turning LEFT. Finally when it came back again he put it on the other way, and it would barely run! It was a fractured wire that only acted up on RIGHT turns.
Subsequently, my test tracks are a flat figure 8, so both left and right turns are tested.
Lesson learned, be careful of a too simple test layout, since your customer will almost surely have something more complex, different, etc.