I don't know too much about PT6's and PW whirly thingy's but Fuel + Sparks + a bit of air = lots of lovely flames - in the correct place of course.
if the AFM gives advice on the use of igniters, continuous or other wise it may stop a bad hair day if you comply.
Some Operators have issued internal memo's to restrict the use of igniters on replacement cost grounds ignore them.
It costs a lot more to replace an A/C let alone the grief it can cause on a personal level.