[thomasguide]

As a cook I find the squeeze actually sort of frustrating. Sometimes it usefully delivers the right amount of ketchup (or mustard, or whatever) to its destination; mostly it splatters. In any case I still have to use a knife to spread it around.

Solving the leaky bottle upside down problem is too narrow a focus.

[jhugo]

The trick is to give the bottle a vigorous single shake before opening it, so the air is at the end away from the nozzle. Then there's no splattering.

[LargoLasskhyfv]

McDonalds does that with cardridges in a (don't know the exact word) squeeze gun, and it mostly comes out in the same volume. They also had funnels for ketchup and mustard, where you pushed once, and got more or less the same amounts per push.