Have calculated that traveling to Russia will cost me five months worth of lost writing time. Three months of consulting to make enough money for airplane tickets and food and transportation, one month there, and another month getting back into gear once I'm home in Seattle. A visit to Russia always kicks me out of my calm daily productivity, and I have to leech out all negativity and stress and desolation that I've absorbed there before I can relax and focus on writing. Usually it takes as long as I've been absent.
This is good to know for the future. Now that I've calculated, it will be easier for me to say no to future trips, so as not to jeopardize my writing. Live and learn. (However, in that month I'll probably acquire enough material to keep me writing for a year.)