I have been driving turbo charged cars continuously since 1985 and have accumulated almost 700,000 miles between (4) cars. My current one had only 120,000 so far. I have never had a turbo failure.
Unless I was running hard in boost for an extended time immediately before stopping I have not treated the motor any differently than a non turbo. After running hard I would let the motor idle for 30 seconds or so before shutting off the engine.
There is no real need for a turbo timer IMHO.