Consider it like this:

- is like an envelope to put some money inside that you want to give them to somebody and do not want others to see it.

- once you get that envelope with money, if are not too much money, you usually keep the envelope as it is, to use it later, either you give it to somebody else with the same envelope or you just take out the money from it and give them in hand (LN).

- if are a large amount, you take out part of them and put them into a safe (LN or onchain) for keeping. You are keeping only a small amount in that envelope.

I personally will not keep in ecash mints more than 100k/mint. I usually redeem the sats into a private LN node.

Keep in mind: ecash is custodial.