I used a fixed float for anything 10' deep or less when fishing jigs.

One knot, no leader.

When I fish bait under a float, I usually use a sliding float.

It's more personal preference than anything else.
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She was standin' alone over by the juke box, like she'd something to sell.
I said "baby, what's the goin' price?" She told me to go to hell.

Bon Scott - Shot Down in Flames