Then buy already-aged cakes and let somebody in a warmer climate carry the risk. It costs more per gram and far less in disappointment.
Storage matters more than the number of years. A cake in a dry flat at 18C ages very slowly, and people quoting five years are usually assuming somewhere warmer and more humid. In a cold dry place, budget longer.
Normal. I keep a note of any card that dies after a six month plus interval and rewrite it that evening rather than just pressing Again. Turns the failure into an edit.
Also check whether the new kettle has a temperature setting you have not noticed, and whether 'just off the boil' means something different in a taller kettle that cools faster. Four degrees on a roasted oolong is audible in the cup.
Chalky is such a specific word and it is nearly always hardness. Good instinct even before you knew what you were describing.
Filtered deck of the most overdue cards, capped at 100, review that, rebuild it tomorrow. Keeps the main deck untouched and gives you a finish line each day, which is most of the battle.
Two thirds of my own backlog turned out to be nine cloze deletions from the same paragraph that I could not answer in isolation. Deleting them was the fix.
Worth checking your water as well. Sencha is sensitive to it and bitterness that only shows on later steeps is a classic hardness signature.
Eight grams feels like an absurd amount of leaf in a small gaiwan.
Or start at 100 to 120ml rather than something large. Less hot liquid to hold and easier to pour cleanly.