Having worked a while in a furniture repair/refinishing shop, I have seen a few products in the shop that can help shorten the oil finish process. There are professional-grade grain filler products that come in a variety of colors to suit what you want. These products come as a heavy paste, and are thinned with some mineral spirits into a slurry. This can be brushed on, and worked in a circular motion with a coarse cloth, turning frequently until the haze is worked off. Allow to dry overnight before beginning the application of the oil finish you prefer. This product reduced the number of coats I had to apply on my last project to 8 or 10.
I used equal parts Polyurethane Spar Varnish, boiled linseed oil and mineral spirits. In my humid NC climate, it sometimes wasn't dry enough in 24 hrs. to apply another coat. However, the results were worth it. That finish formula came from an old American Rifleman article about High-end professional gunsmithing.