Practical or most effective?
Green Screen work demands the following optimazation points to have it be effective.
- flat even lighting, no hot spots, no dark spots.
- no shadows,
- no reflections,
- the lighting has to be bight enough to register the green correctly, aka no noise.
Additionally, to help avoid hot spots, plan on a fresh drywall/plasterboard for that wall and when fixing, ensure sunk and smooth plastered nails. This will help you get a consistent surface for the green.
A curtain if it can be expanded to be absolutely flat with out any wrinkles might work,
but I think this will be very troublesome.
Painting the wall with the appropriate paint would be more effective.
When to repaint?
Establish a base-line video test, that is repeatable, same lights, same object(s), same camera. Run this in your post production chroma-key video track before each production use, and it should be obvious if the paint needs to be refreshed.
Disclaimer: I have not used this paint, it comes with no recommendations.