I have a Hanna 9813-0 combo ph/tds meter. I keep just enough storage solution - about 1/8" - in my protective cap to keep the electrode wet between uses. I tend to take a quick calibration check often as it only takes a second. I get peace of mind and I'm more confident of the ph reading if the unit tests out to 7.0 in the ref solution and I immediately use the meter. It's usually right on but can drift +/- .1 (one tenth) between uses which is totally acceptable.
Peace!