I mix the oils because of the reasons Jimbo mentioned.
better penetration, it drys quicker, leftover oil can be removed more easily.
The orange oil is much thinner than the tung or linseed.
I use to thin the oil with white spirit "turpentine", this works well, but although I like the smell of tung, I like the smell of orange much better.
perhaps I vary the mixture between 15/85 and is 30/70 % on "feeling" but no more than that.
I don't mix 50/50 but I will try that nexttime.
I dip my small objects and hang it so the extra oil can flow down.
then after a couple of minutes I rub of the extra oil and hang the object to dry.
most of the times (with baltic birch) this takes no longer than 1 or 2 days.
if necessary I polish the object and repeat the process.
I make my keychains from 1/4 x 2" hickory "ply" bed frame.
this dries quicker and when I'm in a hurry I use my wifes hairdryer to speed up the process.

works well for me.