Don't get so wrapped up in the "I can make anything on the CNC machine!" mentality that you spend ten hours making a single wheel when you can buy a
Colson wheel for $4.50 (and with minimal custom machining) and have it do the same job.
It's all about the cost to benefits ratio, or the return on investment. It it makes sense to machine it via CNC, do it. Otherwise, don't.
Engineering is not about designing everything as custom parts, or making it all "in-house". It's about finding the most effective and efficient solutions with regards to cost, time and resources.