Temperature control is most important during active fermentation, once fermentation slows or ends there is no problem letting the beer go to ambient.
Are you using a temperature regulator with your brew belt? I would recommend it, that's what I use and the brew belt cycles on and off as necessary to maintain the proper temperature, usually for about a weeks time and then I turn it off usually.
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The Commune Brewing Company-Perfecting the "art" of beer since 2010