A quick check for DEL-HND-DFW-IAH gives a distance of 10,305 miles (one way). This is what a basic (not elite) AA member will be earning on the most expensive PE and J fares on JAL. For the cheapest PE fare on JAL the mileage would be only 50% of that. So if the ticket is ca. $2,000 you always will be better off with AA flight numbers. For the cheapest PE fare this threshold drops to ca, $1,000.
For your itinerary, I do see one way fare of $1,248 that books JAL in R (100% mileage earning). This would be much better than booking all AA flight numbers. I would also stick with booking DFW-IAH with JAL flight number. Sometimes AA prices connecting segments ridiculously low like $5 I saw for RDU-CLT flights.