The answer is…it depends.
If you have a nerve palsy (III, IV, VI) exercising (called orthoptics) doesn’t do anything UNLESS you are having surgery. Then the best ophthalmologists will prescribe it prior to increase your chances of post-operative flat fusion.
If you have a decompensating phoria or something in the convergence insufficiency continuum, where your eyes are capable of alignment, but the drive is intermittently insufficient, exercising can help, but it’s temporizing.
Depending on the issue, prism or extra plus power for reading can help too.