not clear as to why all at once would be better than over the seven years?
Limitless reasons but a couple might be if you bought a lot of equipment in a short time span, maybe 3 vans and take 1 now and other 2 over the long term. If you had a huge profit year that was abnormal, like say a couple major floods that kicked you into another bracket.
Lets say you usually make $100k a year over 5 years and then this year make $261k, well you would get whacked pretty hard on taxes.
Depends on your long term growth plans also, what if you plan on making an even bigger purchase next year, or several.
Definitely not an expert... think i average 1 battle a year with some taxing authority over the last 15 years. Can't stand them.