In a single hotspot I can mine in excess of 200t an hour of Tritium, not exactly pitiful, if not ignoring other minerals / metals some other 'sellable' stuff can be picked up along the way too.I'm yet to be convinced on that part cmdr.
Unless I note that there is better yield of Tritium in Hotspots in Icy Rings, I'd much prefer to fill up my Carrier in the bubble @ 50k/T & only Mine for Tritium as a last resort if I drain my Carrier's hold of fuel.
I've yet to see my Mining of Tritium come anywhere close to being efficient, unlike what I find when Mining in Platinum Hotspots for Platinum.
The FC owner need never have to buy Tritium and has the potential to remain 'in the black' for as long as they wish...
As for efficiency in mining Platinum to buy Tritium, it is OK if in the bubble, but a 1,000t of Platinum won't fill up your FC 44,000 LY from anywhere - or even if you are in Colonia, without either mining it or buying from another FC.
But, if I were to be planning an extended trip out (as the OP mentions) an hour of mining will get 1,000+ LY of carrier jump, if only using the FC as a base to explore from before jumping another 500+ LY the time used for mining can pale into insignificance compared to exploration time.
It is the 'normal' debate though, so it is obvious that logic is going to be thrown down the pan as usual.