Just a thought... I think it's coming down to the age of each sat, how much "life" the bean counters are allocating to each sat and how much the customers are willing to pay for each sat's transmission power for their corresponding transponder. The higher the power, the more $$ the bean counters request.

I may be wrong but an example on 87 is the NewsSource transponder. Big bux there, so they are willing to pay more $$ for the extra transmission power (both day and night). At my location they stay at a constant 12.5 db. The Florida channel, paid by the state (money not a problem), constant 12.4 db. The LPB mux, paid by a slightly poorer state, fluctuates between 8.5 to 9.5 db, depending on time of day. The Patient channel which caters to major hospitals (again $$ there), stays at a constant 10.4 - 10.5 db.

When the sats were newly launched, the transmission power of each transponder were most likely not controlled as much by the bean counters in order to attract customers. Then reception was great with the smaller dishes. Jump to the present and we have the current reception experience.