I used to use a half pound cut for initial sealing on the theory that it soaked in deep and fast and I could do two or three quick initial coats fast. Then I realized that a 1 pound cut did the same thing in half the time and had the same results. I'm not a shellac guru, but the 1lb cut seems to me to be pretty good for everything early on. Again, shellac is a forgiving finish substance so I'm not sure it should become too fetishised. Where shellac will bite you in the ass is if it gets too old and starts to deteriorate and gets gummy. If you are at all suspicious that your shellac mixture is over the hill is easy. Just put a drop on something metal and let it sit over night. If in the morning it doesn't chip off in a nice hard chip but has that gummy feel, time to ditch your prep.