5e Spell Slots Short Rest
Short Rest: A spell caster regains mana equal to the level of the highest spell slot available to them at their current level according to the PHB. 3 short rests per long rest. Wizards would for example recover 20 mana at level 10 after a long rest, or 5 mana after a short rest. However, a Pact Magic allows them to regain all of their expended spell slots upon finishing a short or long rest. According to 5e's rules, a short rest is 'a period of downtime, at least one hour long, during which a character does nothing more strenuous than eating, drinking, reading and tending to wounds.' So, in the time it takes a Warlock.
The rules for short and long rests presented in chapter 8 of the Player’s Handbook work well for a heroic-style campaign. Characters can go toe-to-toe with deadly foes, take damage to within an inch of their lives, yet still be ready to fight again the next day. If this approach doesn’t fit your campaign, consider the following variants.
Epic Heroism
5e Spell Slots Short Rest
This variant uses a short rest of 5 minutes and a long rest of 1 hour. This change makes combat more routine, since characters can easily recover from every battle. You might want to make combat encounters more difficult to compensate.
Spellcasters using this system can afford to burn through spell slots quickly, especially at higher levels. Consider allowing spellcasters to restore expended spell slots equal to only half their maximum spell slots (rounded down) at the end of a long rest, and to limit spell slots restored to 5th level or lower. Only a full 8-hour rest will allow a spellcaster to restore all spell slots and to regain spell slots of 6th level or higher.
Gritty Realism
This variant uses a short rest of 8 hours and a long rest of 7 days. This puts the brakes on the campaign, requiring the players to carefully judge the benefits and drawbacks of combat. Characters can’t afford to engage in too many battles in a row. and all adventuring requires careful planning.
5e Spell Slots Short Rest App
This approach encourages the characters to spend time out of the dungeon. It’s a good option for campaigns that emphasize intrigue, politics, and interactions among other NPCs, and in which combat is rare or something to be avoided rather than rushed into.