Habitually using your own machine for non-work tasks often lets you keep certain records of the research process which begat the work, even while the client/employer owns the work itself through SLA/NDA/AOI. This typically includes records contributing to general “personal expertise,” such as query history, bookmarks, generalized notes, and other non-proprietary information.

It also lends to an overall impression of professional sprezzatura when the client can only see a history of master strokes, without the nitty-gritty details of your autodidactic effort.