Nails grow from the matrix, a band of tissue under the base of the nail. Fingernails grow about 3mm per month; toenails only 1–1.5mm. A full toenail takes 12 to 18 months to replace itself entirely.
Any product that improves nail appearance can only do so as new, healthier nail grows out from the matrix. Existing damaged nail does not repair — it grows out and is replaced. This is why Nail Exodus and any nail product must be judged over months.
Claims of clearing a nail in days contradict basic nail biology. Be skeptical of any product promising fast visible results.