Each split ring on a Wanderchain can hold 40 engraved tokens. Any more than that and we'll add on a second split ring that can hold 40 more tokens (for a total of up to 80 tokens!).
For Necklaces, you can fit as many tokens on as you'd like but we think that the sweet spot is ~30 or less engraved tokens for ideal weight and appearance. Anymore than that and we recommend getting a Wanderchain to hold the rest.