Greg,s comments are right on the money.
I've fiddled with this procedure or removing the fuse on my 260E (103 engine) and actually measured the total ignition advance in 1,500RPM increments with and without the fuse.
The only repeatable reasults I got was a slight ignition retard between 1,500 and 3000RPM. Below and above, absolutely no change in ignition timing.
This is why I said earlier that a 3/64 mouse/power increase at part throttle would be the expected results.