The Harvey Head cleaner is designed more for printers which have a small amount of ink stored between the cartridge and print head that can be moved in one cleaning operation. These are desktop printers and the head holds a little more than a ml and maybe 3-4ml storage in the ink stem. So running a head cleaning on a desktop printer with carts above the heads may be useful. Running a head cleaning a day in a 7900 or 9900 printer is like giving a nudge to a rhinoceros. It doesn't really address the problem of the 15ml or so of ink that is held in the ink lines and dampers. It's just not enough of a nudge. And over time the pigment simply settles out.
Always the best thing to do if put the printer into flush when you leave. A set of flush carts is worthwhile over the life of the printer or sometimes with its first use.
EPSON printers with ink inside of it? Things needs to be shaken and used. Epson clearly says so. And then if you're lucky you need just replace the dampers on an annual basis - think of that as rotating tires, changing wiper blades, oil change. Even in the best of maintenance routines the print head can often render itself useless on the newer models - but not maintaining it is worse. If you have to let it sit, I can assure you that the cost of PiezoFlush and cartridges is way less than the cost of a head replacement.
These newer Epson LF printers must NOT be bought without extending the warranty unless you are prepared on an annual basis to replace the print head. Epson is only guaranteeing the head to last 12 months on these printers. The cost of replacement is now much higher as is the warranty extension because heads are not plentiful and the track record on these printers stinks. A lot of people need new heads within the first year and second. This is common knowledge on the internet and users groups.
The INIT CHARGE is performed on all positions and is the only way to put this generation of printer into PiezoFlush for storage. Likewise, it is the only way in which to move flush through the print head in a cleaning operation. You do not have to put flush in every position to clean one print head. But, the INIT CHARGE will move ink in all the positions.
In general, this printer should have its carts removed and shaken on a weekly or bi-weekly schedule. At least 10-15 letter sized or 13x19 prints a week should be printed as a minimum to keep up with the OEM expectations of little use.
Most people can clear the heads with PiezoFlush. Those who ran tons of the powerful paired cleanings have less luck. And some just are not going to be able to revitalize a print head. So preventative maintenance is critical. For those in which the case is hopeless and despair has set in and the printer is now being contemplated for the recycling center - Dana may soon post some unorthodox practices of removing the head and performing the nuclear option.