Stockfish bench surprise

[Jouni]

This is SF 17 default bench with 1 and 6 cores:

bench 512 1 25

Total time (ms) : 104096
Nodes searched : 93675716
Nodes/second : 899897

bench 512 6 25

Total time (ms) : 113035
Nodes searched : 488314553
Nodes/second : 4320029

So 1 core is faster . Is this meaning either 1) 6 core search does 5x more careful search or 2) "depth" is useless information?

[Ras]

Is this meaning either 1) 6 core search does 5x more careful search or 2) "depth" is useless information?

Or 3) this is an NPS benchmark, not a actual search, and "depth" is for controlling how long the benchmark should take.

[Jouni]

Addition: older versions of SF don't behave this way in bench.

[Viz]

depth always was a semi-useless information since the implementation of lazySMP