I would also love to see some input field for this.
Yes, it is quicker but still putting 1000+ items can be "boring". Also what I noticed is that after shift+click I cannot revert to 1 item at a time. For example, I need 50 items, I need to click it 1, then use shift+click to get 51 and if I click on -1 it will do -10. Once I close menu and right click again I can use +/- 1.