Some things rust faster than others...
Since I went back to work 1.5 years ago, I fly about once or twice a month on average. Many of my skills seem to stick around, including landings (just did a pretty decent x-wind slip-to-landing the other day) and other basic things (I try to do an practice engine out landing every now and then to stay in shape, and things tend to go pretty well). Oh, and my gravelly 777 captain voice comes back with just a few radio calls from the old Cessna.
I think some things are like riding a bike. Once you've really got them down, they stay.
My instrument skills, however, take a nose-dive over time. I have made a point of actually hiring a CFII every 6 months rather than just grab a buddy to be my safety pilot because I simply don't feel competent with an hour of two of actual and one or two approaches over those 6 months. This last time (a few weeks ago), I did better than I've ever done (that is, most skills stayed pretty solid)...except as soon as the instructor started throwing partial panel NDB stuff at me, I couldn't keep up with the plane at all; there was a nasty wind that day, too, but when I passed my checkride I could handle that.
As Clint would say, you've got to know your limits. No way am I (intentionally) flying anywhere near hard IFR. I'll punch through some clouds if I've got decent ceilings below me, but if they're down towards minimums, I really don't feel comfortable that I could handle an instrument failure and still get the plane on the ground safely.
So I'll fly on nice sunny days, or cloudy or rainy days as long as the ceilings and winds aren't that bad.
