It is of course up to you and your opponent if you want to use house rules in casual gmes, just be aware that in tournament games that IS the rule. I believe it’s supposed to reflect the timescale of having to reposition it; hooking it up to the Sd Kfz 250, etc. There is also of course the stacking rule that prevents the Half-Track from entering the same hex.
However the 88mm Flak 36 in particular was designed to be used for Blitzkrieg attacks and was supposed to be much easier to move… although again it’s questionable under the 1 minute per round timescale. Personally I think it should have at least had relocate 1, but I play it as is for now; there’s usually not too much of a problem with it.
Pak 40s aren’t bad, but not always enough against units like the IS-3s and Tigers; some of the more common tournament pieces.