It is not limited to suckers. You can snip most any part of a tomato plant that has a crotch where new leading growth can originate. Either place the cutting in water or place it directly into potting soil. About 80% of my recent cuttings took root and are growing vigorously now.
Eclectic gardening style, drawing from 45 years of interest and experience. Mostly plant in raised beds and containers primarily using intensive gardening techniques.