TL;DR: yes, it sounds like you've understood the idea.
The long version, just to be on the safe side:
The basic idea of "missing the reshuffle" is that you'll be able to play the cards at the bottom of your deck less often than the rest.
Let's go over an example. Let's saying you're playing the "first game" recommended kingdom from the base set, and your first two buys are Workshop and Remodel. At the end of turn 2, you shuffle.
Scenario 1: your cards, in order, are ccceW cceeR cc (c=Copper, e=Estate, W=Workshop, R=Remodel). You play Workshop on turn 3, you play Remodel on turn 4, then you shuffle again. Let's say you gained a Village, bought a Village, remodeled Estate into Smithy and bought a Cellar. You shuffle again. The cards in your deck, in order, are cc-eeW ccccR and more stuff. The two coppers before the dash are the ones that were at the bottom of your deck after your turn-2 shuffle, the rest are the cards that go below them after shuffling. On turns 5 and 6 you can play your Workshop and Remodel again.
Scenario 2: your cards after the turn 2 shuffle are ccceW cccee cR. You gain a Village and buy a Village on turn 3, buy a Village on turn 4 (perhaps not the best idea), then reshuffle. Your cards at the start of turn 5 are, in order, cR-cce, cccWe and then some more. On turn 5 you play Remodel, on turn 6 you play Workshop, and so on.
Note that in scenario 2, by turn 6 you had played Workshop twice and Remodel only once. Compare this to scenario 1 where you played both of them twice. That's the essence of missing the shuffle.
If you like, you can think of "a shuffle" as a set of cards: the cards you will have in hand and be able to draw before the next time you shuffle. In scenario 1 those are 5xc, 3xe, W, R. In scenario 2, they are 6xc, 3xe, W (but not R). In scenario 1 you have 2xc miss the shuffle; in scenario 2, cR miss the shuffle: you won't get to play them before you reshuffle (which is usually a while if you don't see all your cards every turn).
Let me work over an example with Minion.
Let's say your starting hand is Minion and 4xEstate and you have an empty discard pile. You play Minion for cards and draw Minion with 3xEstate; now 4xEstate are in your discard pile. You play Minion for cards again, you get Minion with 3xEstate again, you Minion for cards again (10 Estates in the discard), you 4xMinion and your deck is now empty. You play 3xMinion for money. If you play the last Minion for cards, you'll shuffle your 10 Estates and draw 4, leaving 6 on the deck. Then, after having bought something, you discard your 7 Minions and draw a hand for next turn. That hand will be 5xEstate. You'll have one Estate on your deck, and your discard pile will be 7xMinion plus the card you bought ("and for $6... the last estate"). You'll have made all your Minions miss the shuffle.
Obviously a hand with 5xEstate is super duper bad; you'll do nothing for that turn.
Okay, so that's a highly contrived example: misplaying the last Minion set you up for the worst turn possible. If instead of discarding Estate you had discarded, I dunno, Steward and a Silver and some other cards which are fine and decent cards but which won't help you find your Minions, you won't be seeing all your cards on the next turn, and thus you'll (most likely) have a less powerful turn than if you had more Minions in your draw pile.
I hope this helped.