Coolant at 2.5%?
Go much higher, we use 10% for tapping 6061 in all sizes from 4-40 up to 1/2-13.
What drill size are you using, we use 13/64 which gives about 75% thread maybe a bit less.
Do you Repeat Rigid Tap?
Normally if the thread is deeper than 1-1/2 diameters I will Repeat Rigid Tap making the first entry just over one diameter and the the rest at about 0.75 diameter further for each one.
For through holes use spiral point taps.
For blind holes use sprial flute taps.
Run at 1000rpm or faster; this gives better chip flow.
You should be able to do thousands of holes per tap; although you should cut off at about 1000 and start using a new tap because they do dull and cut undersize.