Don't we all want to capitalize on wall speed whenever possible?  You CAN - as long as you remember to streamline!  When you're tired in a practice race or set, it's easy to slip into lazy habits of bent elbows, separated hands, etc., but just think of how that little loss in speed adds up!  Plus, the more you slack in streamline, the faster you're building THAT into your muscle memory instead of the good habits you need!  Here' is a re-post from our site from May, with a very good visual of how much an impact streamlining has:

Even what I call a “lazy streamline” increases your drag by 7%, people.  Let’s tighten up and make some DRAG-REDUCING muscle memories!