I have not kept track because I do not care about how much the "discount" is, only that I pay the lowest price. With that said, I use my TSD card for all fill ups because I have dual tanks holding 275 gallons and 25 gallons of DEF.
I often use out of network stations that have a lower price without a discount than an in-network station with a discount. My biggest savings so far on a single fill up was $170 from the listed price, the in-network station would have saved me about about $90, the out of network station saved me an additional $80.
I check all fuel prices in the area for commercial filling stations then pick the cheapest. Sometimes in-network is cheaper, sometimes out of network is cheaper, and again I alway use the TSD card. My use of the TSD card has nothing to do with vehicle size since I still have to get into regular gas stations to fill up the gas tanks on the toy hauler.
2014 Volvo 630 Tandem 2016 Chevy 3500 DRW, crew cab
2016 Fuzion 325T, 675ah AGM, MSH 3012 inverter, 1400w Solar