The tax is payed on the job gross price, which is the index fee with some modifications, not the estimated item price increased by the index fee (with modifications). Assuming 5% index fees, and 5% tax, you pay 0.05 * 1.05 = 0.0525 = 5.25% fees, not 10.25%
As you said, the more convenient manufacture index is most likely where you have to spend more “effort” hauling (either hauling stuff yourself or paying others to do it).
The reason DC2 and friends make good yields is exactly as you state: people who login only once per day (or once every few days) will prefer running other jobs which have higher per-job (but lower per-running-hour) gains, as they won’t reschedule every 3hr interval, providing for less competition for DCs on the market. The same goes with most small and medium sized ship modules, damage amps and ewar mods. Starting with BS and suicide BC modules, a regular BPC can be scheduled to run for 24 hours if all available runs are used, which is why there’s more pressure on the market price of Cruiser Missiles (Launchers) then on Rocket (Launchers).
For the launchers, the Abyss consumes cruisers and frigates at a way higher pace then CODE can create battleship / marauder module demand, but for ammo, BS are very popular for ratting through all security zones.
Even if the job rescheduling ability is limited, the TE is important. Advanced Components for example are usually required in large quantities, but they can also be directly be sold for profit, as do reactions materials. Many Null Corps have “reaction programms”, so they run reactions but don’t actually turn those reactions into ammo / components, but instead sell the reactions for profit. Reaction material (and component manufacture) income scales linearily with TE, as the Reaction Formulas and Component BPOs allow to simply schedule larger batches as you please, opposed to final product BPC that are limited in the largest number of single job runs.
ME/TE Research and BP copying is good, but invention TE is also significant. Let’s take a look at the Simple Asteroid Mining Crystal Type B II… it’s the lowest manufacturing yield Type B II mining crystal, yet even if you were to produce in Jita 4-4 the yield, at 5.4M isk output for a 1.7M “investment” (according to eveonline-industry.com) is amazing, and the job completes within 8 minutes + modifications, i.e. 3 minutes in nullsec t2 or lowsec faction TE sotiyos. Max out the batch, and it’ll complete and generate 36M isk per participating toon within 30 minutes, well within the time you’re online anyways (it’s 36M “only” if you build in jita, elsewhere it’s more)… the only problem is that the BPC has to be acquired, and that bit isn’t part of the eve-industry computed investment price.
Amamake is one of the highest index-ed systems in new eden, yet the “job cost” of 3k isk for running 100 batches of invention is neglectible compared to the 80M isk in datacore consumption. The non-skill-maxed toon researches at 46.8% success probability w/o aux items, and would likely produce an average of 46 ME2 BPCs each providing 10 runs, allowing it to manufacture crystals that sell for 167M isk more then the input materials’s pice according to eveonline-industry
, remote-scheduled while running the SoE arc with a single toon, as long as you don’t forget to check your jobs for completion every now and then, let’s say everytime you turn in a mission…
Substract the 80M datacore price and you’re left with 87M isk side-channel income while grabbing some faction standings, which are shared in fleet, and can therefore be “sold” for a not-so-insignificant price, too.
In fact, while running the SoE arc, way more then 46x10 crystals could technically be produced with the single toon that is running the arc (or the mining op, or the CTA, or idling cloaky on the blops while complaining the hunter isn’t finding targets to drop on, …), if you had more BPCs. And here the TE rig comes handy: Amamake’s public engineering station has a T2 rig, in highsec it would have taken +35% time to research in a similarily configured citadel… to run a 1000 runs research job, it would take 10 days in Amamake, 14 in Perimeter, and more then 20 in an NPC station which aren’t just unrigged but also lack the engineering station role bonus, too. Again, using 10x100 run research jobs instead of 1x1000 run jobs of cause is an option, assuming you’re not researching something else already… even then, it’s 1 day in amamake, “basically 2 days” in Perimeter, and “basically 3 days” in Thukker Tribe Land.
As each BPC provides a user with the ability to make 3.7M isk right there in jita w/o undocking or logistics or anything, and consumes an average of 1.73M in datacores (less if the research toon is more skilled then I am) but require you to undock and fly to at least Perimeter to do the research, there’s a 2M gain window to sell the excess BPCs to corpsmates who look at their queues and reschedule more frequently, too.
For the sake of BPC trading there’s certainly items that sell for higher yield then mining crystals, though there are less tools for these then for raw production, and contract trade volumes aren’t public so you need to watch the contract markets on your own to analyze what prices cause trade.