arvados_fuse's ProjectDirectory class uses arvados.util.list_all:
contents = arvados.util.list_all(self.api.groups().contents,
self.num_retries, uuid=self.project_uuid)
arvados.util.list_all doesn't set a limit either, so we get the API's default limit of 100 items per page.
Suggest modifying arvados.util.list_all (in source:sdk/python/arvados/util.py#L365) to do something like
kwargs.setdefault('limit', sys.maxint)
That way, the API server's MAX_LIMIT (currently 1000) will determine the page size.
The rationale is that, once the client is in an API request loop that it won't exit until it gets all of the items, it's never a good idea for it to get fewer items per API request. Getting fewer items per page only makes sense if the client has some chance of doing something else (exiting the loop or processing a subset of results) before receiving MAX_LIMIT results.
(ArvadosResourceList#each_page in source:apps/workbench/app/models/arvados_resource_list.rb#177 needs this fix, too.)