Different shoots act differently summer or winter. With viburnum, no matter when it is cut it will check if not handled properly. On the other hand I can cut sourwood shoots any time of year and peel them immediately with no bad results. I've even cut sourwood, peeled the bark and laid it under my wood stove for a week with no checking. I don't think I've ever had a sourwood check.
Many of these shoots grow in thickets. That's where you'll get your best, straightest shoots. For me, late fall through winter are the best because there are no bugs, no snakes and a more open visibility for spotting potential shoots.
I collect shoots all year long as I walk the woods. I always carry a pair of hand pruners and a folding saw just for this reason but my best shoots come in the winter.