This is costing the Chinese massively in Satellite resources.
Photo reconnaissance satellites typically follow a polar orbit. This goes over both poles, whilst the earth rotates underneath, so they spend equal amounts of time in the northern and southern hemispheres.
The timing of the orbits puts them over their targets early in the morning or late in the afternoon, in sun synchronous orbits, to get 3D perspective.
To change orbit to look at a different target uses up manoeuvre fuel. They obviously only have a finite amount of this so using it is incredibly expensive in terms of the life of the satellite.
About 50% right by my reckoning. They
do follow sun-synchronous polar orbits. This gives them global coverage. So they are not "targeted". Hence no fuel used to change orbit.
Yaogan-19 is apparently a recently-launched Chinese spysat:
Launch News Long March 4C launch with Yaogan 19, November 20, 2013 - Orbiter-Forum
Here's a list of times and inclinations for its passes with respect to 42S 95E which is more or less where they've been looking.
YAOGAN 19 - All Passes
(As far as I know the site mixes historically accurate information with predicted passes).
You'll see that it flew directly overhead at 16:47 (UTC) on the 21st March. Also that it is predicted to do so at 16:47 on the 28th of March; and that it did so at 16:47 on the 14th of March, and the 7th, and so on, going back for months.
No changes in orbit.
(NB that it goes *directly* overhead once per week, but that every day there will be at least one pass where it is reasonably high in the sky).