Choose by yard shape, not the biggest area claim
A boundary sketch helps you ask better questions than a coverage number can answer.
Draw the area you intend to water
Sketch the patch, paths, planted beds and places where you do not want spray. Label the usable width and length, then add any slope or obstruction you can observe. A site sketch does not need surveying precision to reveal where a rectangular or partial-circle setting might be useful.
Turn boundaries into control questions
For a rectangle, look for documented width and length controls. For a curved boundary, investigate adjustable arcs and throw distance. Do not assign a product a precise usable area from its maximum coverage claim. The operating conditions behind those claims are often absent from the product page.
Turn a small rectangle into a shortlist
Hypothetical yard: a 10 × 30 foot strip is 300 square feet. A 4,000 square foot maximum claim does not tell you whether the same sprinkler can narrow its pattern to 10 feet at your setup. First confirm independently adjustable width and range in the exact model instructions; next ask about the minimum pattern at the required operating conditions; then observe the two long edges during a short check. Leave the minimum width unknown if the maker does not state it.
Start with an observed setup
Keep the hose route and stable placement in mind. Run a short check according to the supplied instructions, look at the boundaries and adjust. Record the setting you actually use before beginning a catch-can measurement. This is a workflow guide, not a promise of uniform coverage.