So 229/146 are in the 35 but 238/106 are in the 28? I realize this is for administrative duties, but it seems odd that the 28 would need to drive almost past 229/146 to get to 238/106.
Balancing administrative workloads is always a goal and may result in questions like you have.
Also, administrative battalion districts can also be different than response areas. Old FDNY borough organization maps by battalions would not indicate where battalions responded.
Remember when some battalions only had 2 or 3 firehouses during War Years? In the early 1970s, Bns 29, 55, 27, 14, 26 had 2 firehouses while several battalions had 6 or 7 firehouses to manage administratively. The 60 Bn had only 1.