In our previous federal employee surveys, we asked public servants whether they thought they had "opportunities for promotion" within their current agency, and in the public service overall. I broke the data out by occupational group and identified those who perceived more and less opportunity, and more opportunity across the system, compared to within their agency. As you might imagine, those in rather specialized jobs (e.g., agricultural scientists, coast guard radio operators, or dentists) viewed their opportunities as somewhat limited, and generally limited to their current agency. Others, in more generic sorts of occupations, like admin support, program managers, or folks in finance (essentially the kinds of positions that every agency had to offer) had much broader horizons, and perceived rosier prospects.
Folks in HR were up near the very top of the list in terms of seeing lots of possibilities for advancement locally, and near limitless possibilities for them across the system. It was as if they could stroll down the street in the capitol, say "Y'know, I like that office", and have it within a matter of a few weeks (an exaggeration, but you get my drift). And indices of the mobility/movement/turnover of folks in HR in subsequent years echoed that.
As for staffing/hiring times, we too noted declines in average time required. Closer inspection, however, indicated that this tended to stem from managers opting for the most efficient staffing procedures from among those available. The actual average times for those individual procedures actually hadn't sped up, just that more people were using the short cut, and fewer taking the long way. For instance, staffing that opens up a position to the public, or to all public servants (but not the public), traditionally take longer than staffing actions confined to just that agency. And we saw a shift over time towards that latter area of selection. Mean staffing times for all the various kinds of staffing procedures remained largely unchanged.