When balance becomes the limiting factor
A supported split squat and an unsupported single-leg squat are both unilateral, but they ask very different things of balance. If maintaining position ends the set before the legs receive the intended challenge, adding stable support can make the exercise better suited to a strength goal.
That does not make the unsupported version wrong. It makes the choice more specific.
Do not double the number automatically
Suppose you lift 20 kilograms with one leg on a particular machine. That does not establish that you can lift exactly 40 kilograms with two legs. Coordination, setup, familiarity, and the machine can change the comparison. Keep separate records for separate tasks.
Research on unilateral and bilateral training illustrates training specificity, including a trial in experienced rugby players. That population does not determine the best choice for every beginner or daily-life goal.
Count the practical cost too
Training each side separately can take longer. Bilateral exercise can simplify a short session. Unilateral work can make side-to-side differences easier to notice, but an observed difference is not by itself a diagnosis or a reason to force symmetry. Comfort, control, and the actual activity you value remain useful decision points.
