Also, though it may greatly irritate the accountants to say this, and it is always wise to operate in as fuel-efficient a manner as you know how, the variability in fuel-burn per sector is probably of the order of 100-300kg. In other words, the extra fuel burnt may not be noticed in the "noise" of the quantity of fuel burn measured.
Some aircraft fuel gauges only claim to be accurate to within 3% of full load - on a B737 that was about 120 kg, I think.
And also, it will probably only make a difference of a minute or two on a domestic sector. Winds permitting, it might even make you faster.