Ive been diving for almost 30 years and still don’t own a full blown dive computer. I do have a digital dive timer by Suunto that keeps track of each of my bottom times and surface intervals. I don’t push the tables and have done plenty of repetitive dives. Even if your using a computer you need to be able to go back to your tables if it pukes on you. If your going to be doing a lot of repetitive dives and are looking to maximize your bottom time safely then a computer would be great but only for dives where your changing depth frequently. I look back at all the dives I’ve done where others were using computers and there were only a few that the computer users were given more bottom time because of getting credit for spending time at a shallower depth during the dive. If you think about it computers actually go against the basic training of "Plan your dive and dive your plan"