The default value of maxThreads is now set to 10. But I'm wondering if we should avoid defining this value? Because when it is not defined, the default is the number of partitions. In chapter §8.2.6.1, spec 1.0, (page 34):

Specifies the maximum number of threads on which to execute the partitions of this step. Note the batch runtime cannot guarantee the requested number of threads are available; it will use as many as it can up to the requested maximum. This is an optional attribute. The default is the number of partitions.

So if we could avoid defining the default value, we assume that users always want to use as many threads as possible)