I'm going to go with Student more so

kata won't teach you timing because you need a partner for that

kata/forms serve as a basic instruction tool. This is how you move and pivot, this is how you block, this is how you punch, etc etc. You can practice basic and simple techniques together when you are by yourself. Simple body mechanics. again this is basic stuff so the resistance you experience will be at a lower level. Stuff like simple application drills.

As you advance in skill and in your training, then the resistance you encounter should also increase. More sparring and etc.

But you have to start somewhere, and thats what kata helps with. I think kata is a good learning tool, does it teach you everything? no. And eventually as you get better and better the effectiveness of kata on your skill starts to plateau because you already have down the body mechanics and the techniques for the most part. Unless the kata's you do start to change focus. For example, just hitting the air with punches and kicks vs something like San Chin which is more like strength development.

but like I said, at some point in your training the effect of forms will start to plateau, imo at least
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"you're going to work till you wish you were dead and then keep going.." -Sgt Slaughter