Sounds like the most productivity isn't in the pilots flying, but in the rigs kicking in, if "block tends to be considerably less than credit due to rigs".

Is the rig achievable (ie, could Southwest actually schedule a pilot to fly without the rigs kicking in), or is the rig just part of the pay package?

Rig flying tends to go to reserves and peeps trying to keep their block time down for extra work. Being a fairly jr CA, my flying is rigged maybe 2 days per month. I trade to get as close to 8 hours/day as I can.

I didn't state that very accurately, I might have started celebrating New Years a little early. The lines are built efficiently due to rigs would have been a better way of stating it. However, most segments do credit higher than actual block time.

What is James at 15?

A Lance Captain is a captain-qualified first officer--a senior FO in domicile who chooses to complete upgrade but maintain First Officer status.

The Lance can pickup up to 9 duty days of captain flying per month, if they can clear their schedule to be legal for the pickup. The Lance bids at the top of the FO food chain for schedule and vacation, then works to drop FO trips to pick up CA-pay trips. All without having to commute cross-country to sit reserve as junior captain.

Original purpose for the company was to have a ready pool of CA-qual'd pilots to fill any sudden fleet gains.