Being a burst rate shows the line can produce at a certain rate, but does not show the supply base is able to support that. I.e. bunch of parts batched up, run the line quickly, stop when you run out if parts. Saying all lines were at 1k/wk shows internal processing/ production is capable, not just the final line.
If burst production hits your target in actual output(not just rate) that's a really good thing. It means they can hit production numbers in less time than required/ available. That said, they are shooting for 5k-10k per line, so 1k should be burst.
Equivilent number of days per week is a valid point, but there are a couple others to concider as well. The 570 nunber assumes 5 normal vs 7 reported, that the line up time is the same for the reported 7 days as a normal week, and that the build rate was the same each day.
At the end of 2017, they were parts limited (packs, possibly others). So they can only burst build to stock on hand. Because of this, I'd expect they only ran enough parts to test the line to correct issues (as opposed to running flat out on the first trial and then not being able to run more tests till more parts show up). So small bursts in the tens at most.
As they get more sections of the process working, following sections have more parts to work with and can be tested. (Can't finish without packs and bodies, can't have bodies without assembly, the BIW, welding, DU... etc) so there are multiple sub lines that need to operate at the final speed for continuous production. (This can also lead to staggered burst builds which would cut average build rate. )
To me, the last few days build rate comment says there was an increase in rate at the end. 7 days made 793, but the last few days made (1000/7*3) = 429 of those (over half the 7 day production). The all lines working at rate comment says to me that there were no part production/ processing restrictions internal to Fremont (likely also GF) preventing 1k/ week.
Many unknowns, but I don't see anything that contradicts 1k/wk ability (given external parts) We have 0 clarity on how long each line needs to run in a day, but these statements point to less than 24 hours
Lame analogy warning:
A stock gives out quarterly dividends of $1, $1.25, $1.5, $1.75 what would be the expected next dividend? (average, linear extrapolation, max value, other). What of 1.0, 1.1, 1.6, 2, 2.2, 2.3?