If you mean, can you go 7 days without adding anything, other than operating an SWCG, then the answer is yes.

If you mean, can you go 7 days without adding anything and without using an SWCG . . . the answer is, "Not without special prep" *or* using the HiC2 method" (CYA> 150 ppm; FC > 15 ppm 1x per week).