The Sand Pile Analogy
Let's say you're on a beach and had to build a pile of sand that reached 24 inches in height. You'd probably just keep pouring sand in one big pile. Of course, the width of the pile would increase much more rapidly than its height. If you're not patient, you'll give up, thinking that you're not making any progress. But if you persist, you'll eventually build that pile up to a full 24 inches tall, even if it ends up being several feet wide in the process.
As a beginning lifter, just adding weight to the bar is enough to build up that pile in the short-term. The "sand" tends to stack vertically rather than disperse horizontally. But the more experienced you become, the more sand you have to use to get that pile to rise up. The "sand" in our case is training volume.
Set Higher Rep Personal Records
Don't just focus on improving your one rep max or three rep max, but also seek to consistently set and break higher rep records in your core exercises. For example, if your squat improves from 315x10 to 365x10, just how hard do you think your previous 405x1 will feel?
Even if your ultimate goal is maximum strength, you should document and break a variety of rep records. A new 3RM record will still mean "more" than a new 8RM record, relative to your goal, but they all lead to progress in the long haul.