I talked about this for myself a bit yesterday. This year I stole someone else's board. Really just a guy who used to be a paid writer for a Giants fan site -- but he's now a doctor. His board has 150 prospects on it. At some point I will run out of board lol. I am running this much more casually then I typically do because it was last minute. For the GMO I HATE drafting someone I haven't personally watched at least 2 - 3 games of. It inevitably happens but I really don't like it. What I typically do is watch a bunch of players who I think make sense in the areas the Giants pick. When Getty was the GM it was easy because he loved to trade away draft picks... But I will watch probably about 50 or so guys graded in the first 2 - 3 rounds. For the guys I am thinking about in R1 I usually watch a lot of games. But for most of them it's maybe 3 games just to get a sense of who they are and if I think they fit. I'll then sort those guys based on 1) how I feel about them and 2) where they are slotted across a few different boards. I have specific guys that I mesh with a little better that I typically use rather than like the CBS big board or anything like that. For the guys in round 4 - 7 I focus on things I think I need and pull a bunch of names based on those same big boards and try to watch a couple games anyone who I think makes sense. So I maybe watch in a real loose sense 75 - 100 guys myself. But many of them are quick looks does this feel right kind of looks. It's an imperfect system. There are guys who slip through the cracks that I would catch if I had a true big board. Take Quay Walker for example. He is probably a guy that I wouldn't have spent much time with just because I wouldn't have though he was going to be available in a place that represented value to me. In previous years I may not have realized he was a guy I *should* have taken in that slot because I didn't work up a full big board. Using this board was really handy I may need to try and work from my own board in the future. Or even just using it to supplement my own process.
I take a combination of prospect information from several sights and throw down my top 10 or 20 players at each position. Usually I will have a numerical (overall) score for the player or at least a round projection, but admitedly I'm kinda wingin it this year because I didn't think we were going to do a draft. I'm not that in depth with all the film. I watch some, but mostly I watch the post season all-star games (Senior Bowl etc) intently, as well as the Combine, and then I form my opinions based off that, and everything that I've read and seen throughout the season.
Back when I was doing the GMO, I watched at least one game of every prospect in the cut up room if there was one available. The website I used to use had a lot of cut tape of games, but once you got past the top 200 or so, it became difficult to find any and past the top 100 or so, there was usually only one game. The top 75 always had mutliple years and games and that is where I spent the most time. That was a hobby of mine, I used to watch a lot of game film. I wanted to see what the offensive players did when the play was schemed away from them or defensive players, how they reacted when the play flowed away from them. Highlights are nice and a good way to see the ceiling of a player, but to understand the rest of the package, that game film is priceless. I would generally start with a top 300 list from one of the more prominent websites, however, I downloaded the list between November and December, so it wasn't very accurate. I then started doing my studies for each player int he top 100, since there was always film readily available, then in January I would work on moving down the line into about the 150-175 player range and/or players that were "promoted" to the top 100, finally in February I would do a quick study of the remaining top 300. By March I had a pretty good list going and tweaks were made between the end of February and mid-April, but not significant changes. It drove my wife crazy because I always had the computer on. While we watched TV, or sat out on the patio if it was nice weather, I was always watching about 6 hours of game film per day on average. I was also just in sales back then, so when they brought me in off the road and into the office, I had a lot of free time at work... That has long gone since I have a new position within the company.