Does deliberate practice lead to mastery?
The popular answer is yes.
The more nuanced answer, as always, is "it depends"

What determines whether deliberate practice leads to superior performance?

In Range: Why Generalists Triumph in a Specialized World, David Epstein, quoting psychologist Robin Hogarth, makes a distinction between “kind” and “wicked” learning environments.
 
A kind learning environment is one which has:

✅  Well-understood Rules

✅  Simple cause-effect relationships, and 

✅  Repeating/predictable patterns

Sports like Chess and Golf fall in this category.

Here the key to mastery is deliberate practice.
 
On the other hand, a wicked learning environment has:

❓ Unclear rules

❓ Few repeating patterns

❓ Feedback that is delayed or inaccurate

In this environment, deliberate practice has limited advantage, because your practised strategies may not be suitable for the unpredictable and novel situations you encounter.

What works better in a wicked learning environment, is learning in a variety of contexts, which develops your ability to quickly learn without prior experience.
 
Depth of experience is an asset when you are in a kind learning environment, while broad/varied experience wins in wicked learning environments.