I'm of the school
of having cruising dock
lines for a variety of situations...and day to day lines that sit in the sun and get constant chafe abuse because they are always in the same configuration.
If tie to a float...tie her tight...if tied to fixed...plenty of slack is the usual rule
So all you need to tie to a float is from boat cleat to dock
cleat...tight (though you can have extra and trim off chafed areas as they occur)...in many cases you don't need true springs...but I still like at least 4 lines on if you leave her for more than a few days at a time.