shooting out and about on locations, my gear gets put through the mill changing lenses etc. Time is money right, so recently I was uploading photos and there were specks everywhere. How often does everyone send there equipment out to be cleaned. Sensor cleaning more specificly. I've sent things out now every 6 months or so. Less if I don't have to.
I rocket blow every time i change a lens..
Apart from that i wet clean every 2 weeks as we live in a dusty environment here.
A good thing to learn is cleaning your own sensor, its really very easy and there are guides and instructions everywhere on the net..
All I do is rocket blow before and after each time I have used the camera. I have never had a problem with dust on the sensor, so no comment about that. Just be careful on how you change the lenses when on site.
You can clean a sensor in under an hour, even if you do it a slowly as I do. There are wet and dry methods which work well. I have a cleaning tool that is an orange sticky bar on a white stick that I take when I travel. Lately airlines are really fussy about taking flammable cleaning fluids on the plane! I use the wet method at home sometimes and sometimes just the tacky tool, depending on how stuck on the spots are. I also have a sensor scope that makes it easier to see the spots while the camera is open for cleaning.
If you shoot wide open, you will probably never see many spots. At f/22, you will see all of them. I have a 28-300 and a 100-400 that are pump action. I did not have much trouble with the 28-300 but the 100-400 blew a lot of dirt into my 30D, when it was new. Now I don't have as much trouble with dirt. The body I use most shakes the filter over the sensor assembly, and I guess it must help as I have not cleaned a sensor in months, although I am also shooting a lot more with wider apertures lately.
I am a big believer in "if it is not broken, don't fix it.", that said, if I see dirt in the same place in several frames, I clean, regardless of it being the next day, next week, next month...
Sensor Scope is the safe, easy way to clean DSLRs. The cost will probably be less than sending it out once- depending upon which version you get, of course.
When I first went digital, it seemed I was cleaning my chip once a week, if not more. (Changing lenses in the middle of the street while shooting fires can be dusty, I guess. :\ )
I solved that problem with another body and just mounted my long (80-300) lens on one, left the shorter (17-85) on the other.
Also, remember to hold the camera moount ground-ward when changing lenses. Seems to help some.