I use mine when speed is key and there's lots of repetition. A few instances when I might use a t-handle would be assembly (running down nuts/bolt before final torque), oil/trans pans (ditto), and small engines (high torque isn't necessary).
As mentioned, a good detent in the middle is crucial. Otherwise they can be a pain. Old Ferret kit Snap-On t-handles are abundant if you don't mind used...cheap too. They're good tools.
Put a comfortable length extension between the t-handle and socket and you have a speedy, efficient tool.
Scott
Some years back, the ever innovative Blackhawk produced a Sliding T that was 'ball ended' so you could spin it that much easier! I'm not aware of any manufacturer that produces such a thing now though!
Do you mean like this.