Only have 20 minutes a day—is it better to drill N-class prefixes or just talk?

I’m a busy professional working full-time, and I’m worried that if I spend all my time on grammar tables, I’ll never actually speak. I’ve heard about Chickytutor.com for AI-based feedback, but is that effective for someone like me who needs to maximize every 20-minute slot without getting bogged down in theory? I am asking specifically about learning Swahili, not a generic study routine.