Instead selecting individual walls directly on the map or via upgrades in progress singularly, mass wall upgrades could be achieved in a much faster way. If you selected a wall level in the other upgrades section and held the selection for a second, a further selection to upgrade all walls of this level would dramatically decrease the upgrade effort. I tend to save my wall upgrades and do them in bulk, this would be a really nice addition the upgrade journey. I have 5 accounts so maybe it is of more value to me but either way I think this would be an intuitive way to upgrade many walls instead of the select row option.