It aromatises less than test, has a high rate of collagen synthesis which makes it a choice compound for people that train heavy and gives a nice vascular look. Due to its androgenic/anabolic ratio you'll usually want to dose it at roughly double the amount you would test if wanting to add size at the same rate, its a lot more cost effective to simply use test and the AI dose you need would also be roughly the same. The main reason to add it to a cycle would be for the increase in collagen synthesis to help avoid joint degradation and give decent solid strength gains without blowing up, also for the cosmetic effects (where Tren is far superior). For these reasons it makes sense to use it at a lower dose to test as an addition to your cycle if running it for mass rather than a main compound, even then the benefits of using it as a bulking compound are small. Test/nandrolone/anadrol/d-Bol/Tren/s-drol will always be the more optimal choice if looking to add size. It is proven to be extremely good for appetite but peptides or HGH would reign supreme here realistically.
For the record it will not improve your endurance, any steroid is counterproductive to this and I have no idea where this idea came from, yes it increases RBC count but all steroids do this, it does not suddenly feed you the ability to run the London marathon. There is also the idea it effects the brains GABA receptors and can cause anxiety, there are no studies to back this idea and is based solely off anecdote. Take from that what you will. A ten week cycle is fine to run with it also, there is no reason for it to be 'better' at the 15 week mark. Way to many myths regarding EQ.
All in all it's a great compound and personally I consider it highly underrated but it depends on the intended use, for gaining size best to pick something else.