My snake plant has been sitting in the same spot for months and I'm finally wondering if I'm underwatering it

My snake plant has been sitting in the same spot for months and I'm finally wondering if I'm underwatering it. The leaves feel firm, which seems good, but they're not growing much. I water maybe once a month when the soil is completely dry. Should I be checking soil moisture differently, or is slow growth just normal for Sansevieria trifasciata indoors? I'd love to hear what works for anyone else—I only have four plants total so I'm still figuring out individual needs.