The majority of ATT internet is fiber/copper. The longer the copper loop the slower the speed offered as every 100 feet of copper drops bandwidth.
Faster speeds are available at shorter distances using bonded pairs. The current best for ATT FTTN or Fiber To The Node is 100/20 using bonded pairs on K or N card (requires 2 ports on same 48 port card) at under 1000 feet copper. Next is 75/20 from 1000 feet to 1600 feet. The 50/10 as bonded pair is from 1600 feet to around 2700 feet then drops to 25/5, 25/2 and at around 4500 feet to 18/1.5.
Note these are bonded, you could be under 1000 feet, but only one port/pair is available, normal in apartment settings, and thus can only receive 50/10. The 100/20 is (2) 50/10 combined.
In summary, the card, port(s) available as well as your copper loop length determines best speed any address will receive.
If move, your speed tier may increase, decrease or stay the same based upon that particular address capabilities.
*I am an AT&T employee, and the postings on this site are my own and don't necessarily represent AT&T's position, strategies or opinions.