It could be a case of 'just because they can, doesn't mean they should' when it comes to water. (Survive on sparing amounts, that is.)

Once a fortnight is probably fine over winter but round about September you could shift to once a week. Or a thorough soaking and then let the root ball dry out before the next soak.

Anywhere in Oz right now (unless you live in a flat in town) you could put your Dracaena out for the summer so long as you keep it out of mid day and fierce afternoon sun. And give it enough water to cope with the heat.

That splitting may have occurred from water becoming available after a dry spell. I've seen it happen in cacti - and lived with the embarrassment until the new leaves came in :-( . When you shift from the winter watering system to the summer one you could try using maybe half a cup a week until the root system has returned to growth.

Might also have been sun scald if the trunk got hit by even winter sun through glass. Bright light but protect from raw sun.