Whether you have been working with implants for many years or you are just starting to offer this service in your practice, one of the things you will soon realize that sometimes the level of difficulty of the case has nothing to do with how many implants you are restoring or what type of prosthesis you are designing. I find that sometimes the most challenging part is how accessible the implants are positioned in the mouth.
For most cases, the anterior region is very accessible. But for the posterior region, it really depends on the arrangement of the adjacent teeth, the amount of interocclusal space and the arc of opening. With all the multiple variables at play, I find myself that I always need to have a variety of screw drivers of different lengths handy. In some extreme cases, I have had to use a hemostat to loosen up the screw for removing the impression coping in open tray impression for the posterior region because there is not enough interocclusal space to handle the screw driver and my hand for tightening. Of course, there are tools out there that are designed to access the posterior areas but I am a minimalist and try to use as little equipment as possible to keep things simple. But I would only use a hemostat to loosen a screw to facilitate access because it does come with a risk of stripping the screw. And whatever you do end up using, make sure the screw driver is engaging the screw properly before tightening or loosening the screw.