I am now on my 4th Epson printer.  I run unclog basically 3 times a week and it has greatly reduced the number of clogs.  But I don't think that you can absolutely prevent them.  I have had clogs occur at the end of a full day of printing when all colors have been running and printing for hours on end.  In addition, I run an unclog and then a nozzle check at the start of every print session and after each cartridge change.  You may still get clogs, but much less frequently.

Yes.  Me too.  I have never used anything other than the Epson cartridges.  I have not studied this very scientifically - I have no metrics.  So I still get clogs - unpredictably as I mentioned.  But I am positive that they are much fewer and farther between now that I regularly run the unclog cycle.

I had an epson Workforce multifunction for general use and it kept clogging despite Qimage's unclog routine and its being in daily use.  I put it down to third party inks though their manufacturers denied this.  I got a second Workforce and used only Epson inks and it clogged irreparably just like the first.  I now have a Brother MFC which never gives trouble - tempting fate. I don't pretend these multifuntions are photo printers.

I also have had an Epson 3880 since not long after they came out.  No issues, a brilliant printer so Epson CAN do it.

So, to answer the question how often to run unclog?  Depends on the printer.  For the 3880 - never run unclog seems to work fine! Otherwise try an expensive Epson perhaps using the same class of inks as their 3880 or try a different maker.

Sandy