Only if you've made those summaries and you know the background information that comes with it.
Unless you know the dot point and everything that comes with it, just learning summaries will only give you about 3/5
Make sure its a summary that you understand, you know the background information of ( if its not included in the summary) and look at past papers and check if your summary could answer the questions.
I can't study off textbooks before exams. They stress me out ( the thickness and all those sentences )
Summaries help me study more effectively because i feel more organised and prepared. Everyones different ...
If you're feeling comfortable with it, means its good enough. If you have doubts, go over those summaries and make them more in depth, or read over the textbook first
untill you feel its enough.