I believe these procedure were developed by company, not Boeing, with NTO (No Technical Objection) from Boeing.
Several companies do it, several others do not, so it's unlikely to be a Boeing requirement.
Having operated in companies on both sides of the fence:
- yes, it is time consuming, in fact in certain conditions so much so that holdover time can get compromised if copying with procedure;
- no, it should not be omitted if possible as there is a method to the madness;
Either way, good airmanship should be used when deciding to follow procedure:
- yes, it would make sense to depart and not return to gate to get deiced again as holdover time is now compromised having meticulously followed procedure (ps does your company allow you to continue checklist or do you have to wait for cycling of flaps, as this can significantly increase the time required to complete the checklist in its entirety);
- no, it would not make sense to forego on this procedure if eg freezing rain has fallen on a sub-zero airframe;
- no, it would not make sense to complete this procedure if only light frost was observed prior to flight, no (visible) moisture was present during time on ground nor precipitation, and temperatures are increasing above freezing...
A better ruleset would be very welcome, as the current procedures established by some airlines are way too restrictive, though from safety types on here very likely applauded for thoroughness of company.