Crosses will typically use 2 feet less than the mains. If you string the same racket often, you will notice how much cut off you have after the mains and crosses. When looking up string patterns, they are usually pretty generous when it comes to string lengths, even with a DW.
It's always good to have a starting clamp as a bridge, just in case, no matter what.
Machines: Gamma 6004 2-point w/ Wise 2086 & Babolat Sensor Dual