Plan for your worst week, not your best
Study plans are usually built for an imaginary week with no illness, no deadlines and no family obligations. Then one bad week breaks the streak, and the plan is abandoned rather than adjusted.
Set the target at what you can do in a bad week — one session, ninety minutes — and treat anything above it as a bonus. A schedule you can keep at your worst is the only kind that compounds.
Protect the deep block
One protected ninety-minute block, phone in another room, achieves more than five fragmented evenings. Put it in the calendar as a real appointment and defend it the way you would defend a meeting with your manager.
End every session by writing the next action down. Starting is the expensive part; a note saying 'implement the validation split' removes it entirely.