Thank you @dbkluck for articulating so clearly and in detail the many commendable features of the legacy app that have not been brought forward into the new app.
For long-term users, the legacy app is so efficient: just launch into your daily study routine, adding new words whenever you get bored or let the algorithm add them for you, trust the algorithm to meet your learning needs just in time, then when the timer hits your set study interval, quit until tomorrow.
Simple, elegant, brilliant, and exactly what we need to keep using Skritter.