Apples course was actually the very first Blender tutorial I did, shortly after its release. Somehow Zach managed to squeeze in so many useful bits that, despite being a rather simple course, it laid great foundation for my Blender learning adventure. I came back to it probably a milion times to remind myself of some cool tricks I've forgotten over time. Maybe even more importantly, this course made me fall in love with Blender from the very first cube. These days I've moved my archviz workflow completely to Blender and I've never been happier. It's probably safe to say that a fair portion of my comfort working with Blender comes straight from Zach's tutorials, especially the apples course!