Which way of these 2 ways is more correct to count these simple delay days? use straight days or effect?

Which way of these 2 ways is more correct to count delay days?

Steel was supposed to take 95 Days, it took 142.  = 47 Day difference = 47 Day Delay.  You could argue the contractor is "owed" 47 days.

Steel was supposed to take 95 Days, it took 142.  But 2 of its successors completed in the meantime and each were 10 days, so is the delay 27 Days?  You could argue "the effect" was 27 Day delay.

(to further complicate it the contractor delayed the successor to the above successor 16 days so in my opinion that is concurrent, and so 11 is non-current, 16 are concurrent of the 27.) - but maybe that is complicating it too much.

Which is correct? ie, more used/legal in the USA.