If you vape 5 ml a day, at 50/5, you'll go through ~1L of VG/PG a year. Actually less PG as flavors typically come in PG, and if you
buy your nic in PG that also counts. Rather than buying a gallon (~4L for simplicity) is way overkill. Me? I but a quart/liter at a time. I still have 3/4 of a bottle of PG sitting around as I mix 70/30, maybe ~10% flavorings and nic in PG. I just finished my first quart of VG a month or so ago. As I don't expect any supply issues with that stuff, having a GlyCube of 4 gallons stashed somewhere doesn't seem to make
sense in my circumstance.