<font color="blue"> </font> once started it will go on its own
<font color="black"> </font> To a point only! On steel that is 7 ga to 1/4" you may be able to cut another 1/2" to 3/4" without preheat, but you would really lucky to get that far. On lighter guage metal, you wouldn't have enough baseline heat to continue cutting much, if any. On heavier metal...well, since we're talking entry level, it doesn't deserve much comment.
The point that I'm trying to make is that it can be done to a point, but it's not worth the frustration in attempting to do it just to save acetylene.
Before becoming a desk jockey, I welded production for 10 years (mostly 3/8" to 1/2" mild and stainless, manual, mig, and sub-arc). My dad owned a welding shop, so I also did my share of mainenance welding.