One issue I face when playing altissimo is wading through the visual clutter of ledger lines above the staff to identify the right note. To tackle this problem, I created a flashcard set that trains me to recognize notes. These cards include notes all the way up to super-high C — a rare occurrence in real life, where you rarely see anything above altissimo A. After receiving feedback from someone who faced a similar issue with notes below the staff, I added notes below the staff down to low E.
The complete set consists of 17 cards. Each card shows you a note and asks you to name it. You can repeat the cards as often as you like — as you would when practicing a loop to work on awkward fingering. A few minutes every day on these cards should improve your note-reading accuracy. Give it a try and see what you think.
There are two versions: the Easy Version gives you instant feedback when you make a mistake, while the Advanced Version takes you through the complete set before showing your final score.