מִזְמוֹרֵי תְהִלִּים וְכֵן שְׁאָר פָּרָשִׁיּוֹת מִתּוֹרָה נְבִיאִים וּכְתוּבִים שֶׁאֵינָם שְׁגוּרִים בְּפִי הַכֹּל, אָסוּר לְאָמְרָם בְּעַל פֶּה. אֲפִלּוּ מִי שֶׁהוּא יוֹדֵעַ לְאָמְרָם בְּעַל פֶּה, יֶשׁ לוֹ לִזָּהֵר שֶׁלֹּא לְאָמְרָם בְּעַל פֶּה. וְסוּמָא מֻתָּר
Kitzur Shulchan Aruch 1:6
According to this law, one cannot say a section from Tanach without the text unless it is something that people often say by heart. What falls under this category? For example, would the portion of the Torah (the commandment for the Kohanim to bless the Children of Israel) that follows the Blessing on the Torah count as something we often say by heart? What about Shema?