Being in the consulting side you have to consider that the Consultants business is also affected by a lot of irregularities and by a higher tax burden that the FTEs . I believe that 3X is an OK figure, I have seen places in which 5X is possible depending on the undertaking at hand. Meaning:

Longer term -rate usually is less

Short Term with high pace (including nights)  - rates go up steeply.

Just my $0.02