Bonjour Anna, "Matin" is usually used as a division of time or an indicator for an amount of time, for example: Je suis en voyage depuis trois jours; ou, je vais jouer basketball ce matin. "Matinee" is used to indicate a duration of time. Ex. Nous avons travaillé pendant toute la matinée.

# [an, jour, matin, soir] [année, journée, matinée, soirée] You use the forms without -ée: ~ where the frequency is highlighted: Je travaille chaque jour (I work every day) ~ with numbers: il a six ans (He is 6). But if an adjective modifies the noun as well, the -ée forms are used: trois bonnes annees (3 good years) the words with the suffix -ée express the content of the object. Hence, you use the -ée form: ~ where the duration is highlighted: Je travaille toute la journée (I work all day) ~ with adjectives: une année horrible (A horrible year) To be continued... =) [ you say l'année 2009,l'année 2010 but l'an 2000 ] and other rules and other exceptions...

That's a rough approximation but u can use it as a trick: "matinée" is far more used than "matin" in core grammatical functions such as subject or object. Same holds for "journée", "soirée". Note that the pair "an/année" has a deviant behavior.

matinée is the amount of time inside a matin so the morning (matin) is the "enveloppe" of the amount of time inside it(matinée) so yes when you want to outlight the frequency rather than the amount of time you choose matin instead of matinée exceptn if you want to stress every & each amount of time in the morning for an action that implies duration in time:ex chaque matinée de cette année là je la passai à m'entrainer au baseball afin d'acquérir ma balle tombante