That and with printer if you don't print you dont pay.
Certain other tester forces use to use "ink" every day even if don't want to test. We don't know yet if Maven will force user to perform a test x times per day as a requirement.
May be worth expanding on this.
Printers:
Inkjet printers suffer from dried nozzles. So there is some validity in the cleaning process and/or periodic purges. There is certainly valid concern that it is done in excess, leading to inflated consumables usage. The longer the printer site, the more likely it is that the nozzles will clog with dried ink. Use it or lose it....
Laser printer. There is waste toner and depending on topology the transfer rollers may need to do a small purge, but as with inkjets, there is some valid concern that this is done in excess to inflate consumables usage. They can sit indefinitely, though settled toner may need a shake to prevent clumping. Some printer due this and it causes waste, literally shaken out of the cartridge and then the roller must be purged as well. There is no need to "regularly" use a laser printer.
Automated Reef Testing:
GHL - Profilux. There is no "waste" consumable. The pH probe is kept wet between tests. It could dry out if tests are not done for weeks at a time. The reagent is acid. It does not clog tubing.
GHL - ION-D. The "probe" is an ION-Selective sensor. It does not use "reagent" -- it uses reference solutions. The probe itself has a shelf life and MUST be rinsed very regularly or it will stop working. The probe must also have reference solution flowing through it or (over it, in some designs) during sampling. There is a lot of waste and there is a very real requirement for the probe to be "used" daily, or even more frequently. Use it or lose it.
Other pH based KH testers - If the probe is kept wet, then it will degrade at its normal rate. Reagent is acid, it will not clog tubing. There is no requirement to do regular tests.
pH based KH differential tester - Uses CO2 equilibrium There is no reagent and like the other pH based testers -- there is no need for regular tests.
Colorimetric Titration Testers - This is where things get messy. Some reagents have a high propensity to crystalize or create deposits as they evaporate or residuals react in shared fluid paths. Some designs are better than others, but there is a realistic requirement for somewhat frequent testing to prevent clogs or partial clogs.