Why the timer matters
Most card rip apps store your pull for a while, then sell it back for you if you don't choose. That's convenient for cards you'd sell anyway, but it can take the physical card away if you wanted to keep it.
Know the timer before you rip, and request shipping on anything you want in hand.
Short windows
Trove's homepage says its buyback is 100% of FMV for the first minute, 93% for the next hour and 90% after; its Terms say 55 seconds and let Trove change or withdraw offers. Underdog Rips sells $1-pack cards back after 60 minutes.
PrizePicks gives 24 hours from opening the pack. PackRipper reports Packed auto-sells after one day; Packed's own terms say the Vault tab shows the current window.
A few days
Packz sells cards back after 72 hours in your collection, and its terms make buyback offers discretionary. Underdog Rips gives 3 days on regular packs, and Collector Crypt's buyback offer on Jupiter Gacha closes 3 days after the pull.
About a week, or no deadline
RotoWire reports Rips by Triumph lets cards sit in the vault for up to 7 days. CrownCards' terms allow holding items for up to seven days, after which it may require you to ship or sell.
Tilt Rips offers free vaulting with a 90% sell-back and no forced deadline.
Timers aren't value
A longer window gives you time to check sold prices; it doesn't change what a card is worth. None of these terms say anything about what a pack will pay out.