one other problem with that method is that all your block seams end up on the bias. it helps to press extra carefully to ensure the blocks start out even and properly sized. you should sew extra carefully for the same reason.
if you cut your strips on the bias to start with, you will have to sew carefully to assemble them and to make the tube. however, when you cut the tube into blocks, they're easier to deal with because the bias "goes away".
starch the fabs stiff as a board and the whole thing is easier no matter how you cut your strips.
as to disappearing points ... who but you will know they weren't supposed to be that way all along? just because they don't look as expected, don't assume they don't still look just fine. :wink: