I now shoot for 4-4.5mm at the treble end and 5-5.5 at the bass. Those c.3mm or even less seen on Torres' and other old Spanish guitar are incredible
What put the scare deep in my bones was a bridge I nearly completed. It had about 3.5-4mm of meat only and while polishing the slot with a fine file the front block split with minimal leverage. If it would have survived the filing, it would have certainly not survived bringing the first string to half pitch 
Since then I give a solid try to the bridge while working it and before gluing: I slightly bend and twist it, also insert a saddle and push on it. On my latest I also cut the slot a couple degrees slanted back, based on one of your older posts about this. It's a nice trick, and also useful in the possible event of top dipping in front of the saddle. In that case the saddle will go to c. 90 deg instead of being tilted forward...