Whatever perspiration comes from one's Shabbath preparations, HaQadosh Barukh Hu uses to erase all one's transgressions, in the same way that tears do. As such, it is worthwhile putting in extra effort because one's reward is in accordance with the effort that one puts in.
Additionally, one should do all one's Shabbath preparations quickly and with alacrity. After all, if the Queen was coming to visit, wouldn't one make a mammoth effort to obtain everything necessary and put everything in order as quickly as possible? How much more so should we make a concerted effort to prepare for the Shabbath Queen as quickly as possible.
Even if one has a lot of home help, nevertheless, one must prepare for Shabbath oneself, wherever one can (see http://www.atorahminute.com/2018-01-05 ). This is in keeping with what our Rabbis tell us (Qiddushin 41a), that a precept performed by the person himself, is greater than one performed by a Shaliyah (agent).
(See Meqabsiel, 2nd year, Oth 4-6)
Shabbat, Laws of the Sabbath,