most people that are increasing in 5lb increments are people who have trained the lift before, and that is the max jump they can make to make progress. I say, if you can jump 10-15lbs to start, by all means do it....eventually it will taper off and you can make smaller jumps.
but be really conservative about it.. if it's doesn't feel good to u then listen to ur body.. also never compromise form for weight.. if from goes down then it's time to lower the weight..
adding 100lbs to your deadlift can take some time. but if you are new to the lift, it wont take as long as it would for someone to go from say 500 to 600.
make jumps (in weight) as fast and as often as you can, while making sure that your form is decent. everybody deadlifts slightly different. the only real key to remember is to make sure that you have your lower back arched, not rounded. it is ok for you to round your upperback. this (rounded upperback to some extent) is slightly beneficial because it creates a shorter distance that you have to pull the bar. same w/ sumo stance, but that is hit or miss, and it is generally a lot easier for people to deadlift with a conventional stance.
They are right. If your new to deadlifting you may be able to add up to 15lbs every week for awhile. I just started deadlifting this past July and my five 5 rep max was 275 with a max of a little over 315. After just 3 months I now have a 5 rep max of 390 and a max of 420 going for 425 on monday. The difference now is that I am going up by 5-10 lbs instead of the 15 I was. I have been doing the 5x5 followed by a 1x1 every week and its working pretty well.