Sometime when that happen, it make me wonder if the Chinese actually encountered some technical problems with their imported products that we do not know about, so they are not going to sail them often.
There might be a lot of truth to this, as the Russian Navy itself doesn't use it's own Sov's very much.
It appears that many Soviet-era vessels have relatively low endurance and short lifespans.
In contrast, look at China's equivalent in engine design (steam propulsion) and appearance - the single-vessel Luhai class DDG and it's half-sisters the 051C DDG's.
It regularly goes out to show the flag, and has been doing so for about 10 years now - if I'm not mistaken.
Although it was already obsolete when launched and commissioned, it nevertheless served the PLAN rather well on it's 'PR' patrols.
I have a feeling the the Sov's machinery may not be that reliable nor the vessel itself very habitable for long deployments.
The only time I can recall them being used in a PR mission was a visit back to Russia some time ago.
Aside from the transfer of technology issue, I believe these vessels were procured in haste to have something more modern (for the time) for the PLAN to use in the event of a 'hot' confrontation with Taiwan over independence.
After that possibility faded with the defeat of the DPP and Chen Shui-bian, the PLAN now uses them mainly for anniversaries, preferring to keep them in port, not operating these expensive and difficult-to-maintain assets.