Man, I gotta push back on this one. Ray got lucky and you got a clean line, but a 45 degree cut is not some magic rule for every tub. Half the pros I know cut almost flat, like a 10 or 15 degree angle, because a sharper tip lays down a wider bead that actually fills the gap in one pass instead of needing two. Pushing versus pulling is another thing people fight about forever, and plenty of old school guys push the whole way and their work looks fine. The real fix was probably that you scraped it out and started over with a fresh tube, not the angle of the tip. Tip size should match the gap, not some number you read once. A hairline gap between tub and tile needs a tiny opening, but if the gap is a quarter inch you better cut bigger or you'll be laying down three skinny beads that peel apart in a year. If it looks good and it's sealed, that's what counts.