When you're creating your phrases, or using ones you find in obscure books, remember to keep them short. Those long phrases will end up looking like words or some odd outline you won't be able to read in years to come.
Also, if you make some long ones, they will end up on the next line and maybe the next line down. This will cause you to lift your pen, wasting time to get to the current line to continue writing. It will slow you down.
Another disadvantage: you will need to remember them exactly or you won't be able to transcribe. You will pause thinking, "is the phrase 'I don't want to go there today' or 'I don't need to go there today' or 'I don't....' ".
Tips in using those: Use what you use today. Have a key handy somewhere (maybe even a scanned copy on your computer and phone). Practice so you know them thoroughly.
"Gregg Shorthand had achieved the most extraordinary success ever attained by any system in the history of shorthand." John Robert Gregg, 1922