yes, you can do it with the power, what I normally do it do it with the power then twist the final bit down by hand, you can do whatever you want, cordless drills are mean machines and are used and build to do tough jobs, they are made for torque so a little resistance by hand will not hurt anything, your biggest concern will be to not tighten your bit enough if you just speed chuck it with the power, but for most jobs speed chucking works fine, just remmeber if your doing something that requires perfection, no slips or, high torque or weird angles, make sure you tighten it down by hand nice and tight.