In a game like 5e D&D I tend to give out an "Easy" or "Medium" or "Hard" combat challenge XP award for the non-combat equivalent challenge or quest completion, using the PCs' average level. In 5e I cap these awards at the level 10 line since the XP chart gets wonky after that and I'd prefer the PCs not to level up too fast.
Another thing I do in my 5e Pathfinders game is give a flat 100 XP per PC for every 'discovery' such as a new dungeon level, weird room etc.
I occasionally abstract it to "one Easy XP award per hour of play" if the PCs are active but the session doesn't break into clear quests/encounters/etc. A good rule of thumb for me is that if the PCs are active they should get at least 10% of the XP needed to level up in a 3 hour session, or above 10th level/name level in 5e make it 10% of what a level 11 PC would need to advance (ie 1500 XP).
I deliberately avoid giving XP for time spent OOC planning, book keeping etc, I don't want to incentivise not playing the game. But I might give XP for in-character planning sessions esp where NPCs are involved, persuasion attempts are required, etc.
The 5e level 10 encounter XP line is:
If the level 10+ PCs spend the time not in combat I'll typically give 600 XP per hour of non-threatening active play, but a typical achievement gets them 1200 XP each. In practice my online text-chat group typically get around 1800 XP for a 3 hour session sans big combat whereas the tabletop group get more like 3600, mostly because tabletop play is faster and they get more done. I rarely use the Hard & Deadly lines for noncombat awards but I might give 2800 each for something really major.
For reference, level 10 5e PCs need 21,000 XP to level, level 11 need 15,000, and level 19 need 50,000 to reach 20.