Generate daily sketchbook warm-ups that drill one skill at a time

You are a studio art instructor who designs focused daily warm-ups. Every warm-up drills ONE named drawing skill in a short, repeatable block — not a random draw-whatever doodle.

My context (I will fill in):
- Skill level: [BEGINNER / INTERMEDIATE / ADVANCED]
- Tool: [PENCIL / INK PEN / DIGITAL / CHARCOAL / BRUSH PEN]
- Time available per day: [5 MIN / 10 MIN / 15 MIN]
- The ONE skill I want to drill: [GESTURE / LINE CONFIDENCE / VALUE & FORM / PERSPECTIVE / PROPORTION / COMPOSITION / CROSSHATCHING / NEGATIVE SPACE — OR 'ROTATE THROUGH ALL']
- How many days: [5 / 7 / 14]

For EACH day, provide:
1. THE SKILL DRILL — the specific exercise for that day, named and described in 2-3 sentences. Example: 'Confident contour: draw a coffee mug in one continuous line without lifting your pen. No erasing. The goal is commitment, not accuracy.'
2. THE SUBJECT — a concrete, easy-to-find subject suited to today's drill (a crumpled paper bag, your own non-dominant hand, three kitchen objects of different sizes). No rare props required.
3. THE CONSTRAINT — one rule that forces the skill to develop (time limit, no erasing, one stroke per edge, only three values, draw the reference upside-down).
4. REPS & DURATION — how many attempts and how long each (e.g. '5 attempts, 1 minute each' or '1 sustained attempt, 12 minutes').
5. WHAT TO WATCH — one specific thing to notice while drawing (where your line wobbles, where values flatten, where proportion drifts). This turns a warm-up into deliberate practice.
6. PROGRESSION NOTE — one sentence on how today's drill is slightly harder than yesterday's, so the week actually builds.

Rules:
- Every drill must be doable in the stated time with common objects or photo reference.
- Never assign a drill that does not serve the named skill.
- Keep subjects low-pressure and repeatable so the artist returns tomorrow.

Output the days in order as a warm-up plan a sketchbook artist can start the same morning.

Success signal: the output is good only if every day drills exactly one named skill, includes a concrete subject and a real constraint, and each day is slightly harder than the last.