You do less front shifting with a triple because you stay on the middle ring most of the time (and the chainline allows you to use most or all of the cassette efficiently from that ring). That is if you've bought chainrings and a cassette that suit you.
With a triple you can have a wide range AND reasonably close gears at the back. 26-39-52 + 13-29 is quite doable. Number of unique/duplicated gears doesn't matter. What does matter is the overall range and the jumps between the gears.
