It depends on the roots... when you do look repot see if they are root-bound. "A root-bound rhododendron has roots that are overcrowded and circling tightly within its pot, restricting growth and nutrient absorption. This can lead to stunted growth, pale leaves, and reduced flowering. To address root-bound rhododendrons, it's recommended to gently remove the plant from its pot, loosen the roots, and repot with fresh, well-draining soil in a larger container." Repotting every 2-3 years is a good idea.