There's no way to know w/o knowing what the conditions were for your test. Ambient temp, water temp, wind conditions, windscreen, amount of fuel used, etc...
I've built many, many more dozens of pop can alky stoves than I care to admit (was a full on alky-addict for over a year, built four or five a day sometimes) and for an open jet kind of stove, I could reasonably expect to boil 2c of water (about 500ml)in about 5mins, with about an 8-10 minute burn time. Starting with bout 60f degree tap water, at about 50f ambient temps.
I kept notes, but I have had some much faster boil/burn times, and some really slow ones. Google mini bull designs sst if you want to see a fast boil time. I built one, and it was a bit frightening. The mbd nion style stoves I've found to be the most efficient, but slow. I could get a 2cups boiling in about 12 mins, but the stove would keep simmering for nearly 30mins on that same oz of fuel.
Most important with an alky stove is to have a very solid windscreen. The slightest breeze will destroy stove efficiency without one.
My #1 reason for using an alky stove is cost. You can't get a cheaper stove with a more available fuel.