502 is an ok number and the actual number doesn’t matter so much as how you feel. Some guys need to get up over 700 or 800 to feel as well as they want, for other 502 is fine.
Testosterone replacement is just that replacing what the body is not producing and it is meant to be longterm. Watch out for fertility issues if you plan on having kids as T can decrease sperm quality. Clomid or HCG can be used to protect the testicle and sperm quality. It is important not to forget the estrogen as that can increase and needs to be checked. Most men need arimidex to balance the estrogen.
On 200mg per wk of test my range is between 700-1200ng/dl. The day after my shot I’m around 1200 and by day 6-7 I am down around 700. Anything over 800 is optimal and you can float around 1100-1200 with usually no health issues. But I would make it a point to donate blood on the regular. As for arimadex, I got away without any the first couple yrs of trt but then estrogen started elevating a tad and I began using just 1/2mg 3x a week and it keeps me in good range. As for hcg I usually just hit a whack of it every 10-12 wks for 2500iu x 2 wks, and this is mainly because it comes in 5,000iu vials and to use the standard 250iu twice/wk means the shelf life of 30 days aftet constitution will expire before I use it all. I dont want to waste it and preloading pins and sticking in freezer to prolong shelf like after constitution is a pain.