I got into the habit of cleaning my machine at the start
of every sewing session, and with 2-3 bobbin changes if I
am working on a big project without many breaks.
Although my Brother machines say they do not need to be
oiled I do a drop anyways just because I would rather be
sure that it is lubricated well as for it to get "dried"
out from the lint absorbing the oil.
Of course that is just MY personal preference.