> Is it typical for a 13mm+ Ulock in Amsterdam to get broken?
Yes. One thing that still works is to get two different high-end locks and to always use both. Most thieves specialize in one lock only. But I'd still not leave a decent bike outside over night.
Here in the UK, savvy bicycle commuters buy an extremely heavy chain [1] and leave it locked up outside their office. Bicycle locks are a compromise because they need to be light enough to carry. If you don't carry your lock, you can use a massive lump of metal.
Then UK thieves are clueless. The recommended padlocks (SS50C or SS65C) can be picked (search for model + "picked" on youtube) in less than 30 seconds. For bystanders picking the lock looks like you are just too stupid or drunk to use your key.
There's a video where a guy breaks a bicycle lock with a angle grinder, in the middle of the day in a city center. Nobody bats an eye. Breaking the lock doesn't have to subtle.
Because clearly, when stealing a bike, you want the entire neighborhood hear you for ten minutes, emitting sparks everywhere, while you had to bring an angle grinder.
You're supposed to be somewhat discreet when doing that, not warning everyone.
Most people's locks can be cut with a strong set of shears. The other ones are usually not worth spending your time on unless it's everything there is. In which case, like @jacquesm said, freezing temperatures are an excellent solution. More of a middle of the night thing though. Shears work 24/7.
Yeah I think the main benefit of using two locks is that a thief will just go for an easier option. IIRC similar rules apply to home security. It's not only about deterrence; making your house more of a nuisance than other houses is important too.
Yes. One thing that still works is to get two different high-end locks and to always use both. Most thieves specialize in one lock only. But I'd still not leave a decent bike outside over night.