I often use proactive UX in my work, I usually build B2B apps intended to evolve and grow over time so much of my work is designed in such a way that parts can be expanded or modified without having to redo everything. Often the hard part is finding that sweet spot between everything fitting just right in the available space and figuring out what the most important things and what can be pushed out by one or two clicks to allow room for the next "most important thing we haven't thought of yet " in the next update