My experience in China and the Far East suggest that the Russian aircraft operating system relies on Xmas Trees to keep a reducing number of aircraft flying. The Third World is littered with cheap Russian aircraft that have run out of spares or the wherewithal to get them. Even the Soviet Far Eastern Air Force suffered the same fate.
On my first visit to a PLAAF base in 1996 there was a line of aircraft with operating examples at one end and derelict, stripped wrecks at the other. There has been a complete changeover of equipment since then but I would be surprised if the old habits have died. At that time even civil aviation was the same with Russian equipment. At Tanjian there were a group of ex-Aeroflot 154s being used as spares for China Northwest's aircraft. The wholesale transfer to Western aircraft happily brought that system to a close.