The key to a great finish is a good Squeegee Rubber. A sharp edge and firm blade will ensure water is removed from the glass first time, every time.
How do I choose?
A simple rule of thumb - use Harder or Regular squeegee rubber in the Summer and move to Softer squeegee rubber in the Winter.
Does it make a difference?
Yes. The whole idea behind Squeegee Rubber is that you want a little flexibility in the blade - but not too much. So warm glass in Summer, or hot water in your bucket, causes the rubber to soften. When a soft squeegee rubber becomes too soft, stick in a Hard or Regular rubber instead. In Winter when the glass is cold a Hard squeegee rubber becomes too hard - so switch to Soft.
Bear in mind too some channels, like Unger are more shallow and are designed to take Unger rubber which is less broad. Putting a Pulex soft rubber in an Unger channel will result in too much flexibility - allowing water to creep under the blade. So if your using Unger squeegees use Pulex Regular rubber all year round.