Google’s crawl algorithms are constantly changing and evolving. Most of the sites I monitor download daily Google Sitemaps, sometimes even several times a day. And this has been true for several years.
Many factors influence how Google indexes your site and how often. Regardless of whether you use webmaster tools, what determines your Sitemap for your frequency of change, whether you use analytics, your PageRank, etc ...
While I say that the frequency has increased slightly over the past few years, I have not seen significant leaps in recent years. There is nothing to worry if you are not trying to play the system, in which case Google will catch you .; -)