1wk is not bad at all, yes,I found some strains take alittle longer,pwr outage's too in veg or decided to pull 1 or 2 back out to reveg after 3wk's into bloom(4 some reason,forgot why,awhile-while ago),Iwould think yield be effected. I would light on 4 a wk or 2,then back 2 18hrs on,extra shot of B vit and N & keeping the roots moist,careful of not letting them dry out. Had good succes in this way.
Peace