When I was kid we used to to the same, but we made sure both ends were tapped fist, then we used to tap o the middle. That way we would guarantee the cut would be uniform end to end.
I tried this method several times on a Shower Glass 3/8” but the Glass won’t break !!! Any advice ( I have 72” L that I have to cut it to 48” ). Thank you in advance!!!
Just Use a brush to apply the oil on the glass before you cut it with the glass cutter and then place the sodden back part of the brush under the glass on the end of the cut and snap it pushing down.