Have been on both sides. Have worked in FAANG and have been an applications architect at large companies. I honestly have no good solid advice on how to get good at Systems Design. At the root of it, systems design is broken down into 2 things. 1) Having a solution that fits the requirements of the project and 2) Being able to convey and convince other people. For point 1, it's mostly about reading and using architecture and just applying it and hoping it works. It sounds like you have been reading into it so I'm not going to get into the technicals. For point 2, it's something you have to just practice with people. And it's not limited to only system designs. Stuttering doesn't really affect how well you convey a point, only the time it takes you to convey it. If you're good at explaining stuff in general, you'd be good at talking about systems design given you have a solid architecture. If talk with friends and explain things and they just constantly get lost, it's a sign that's telling you that you're not very good at explaining stuff. One other piece of advice for stutterers is that it's better to stutter and be personable than to not stutter and staying stoic the entire interview. Depends on the interviewer of course but most interviews are about how much the interviewer likes you. It leads to them possibly helping you more or even giving you a thumbs up to move forward based on your personality.