I track how long spells or conditions last by just scribbling down the condition and a duration on my initiative sheet.

For example if the Barbarian rages I’ll just write “Rage - 10” and each round I add a tally, when we hit 10 it’s over. So there’s no “extra” tracking, if someone delays their turn I just add a tally mark.

It might be a bit harder on digital tabletops if you have to go in and edit things.

I counter that by counting both the original turn and the delayed turn against spell duration. It lets people continue delaying (I’ll even let them go back to the top of initiative order in the following round if they want) without breaking spell duration too much.

For example:

• I roll 20 on initiative and cast Faerie Fire during round 1, it will last for 10 rounds (1 minute). At the end of this turn, Faerie Fire has 9 rounds left.
• At initiative count 20 on the second round, I decide to delay my turn until initiative count 10. Faerie Fire has 8 rounds left.
• At initiative count 10 on the second round, I take my turn as normal. Faerie Fire has 7 rounds left.

We use “I Know a Guy” or “I Have a Thing” as options for inspiration, instead of just giving yourself advantage. The party loves it and prefers it to improving a dice roll here or there.

It’s been used for mundane things so far, like having some pebbles in one’s pocket to toss and make a distraction, or knowing someone who could assess a gem before going to a merchant and (potentially) getting ripped off — and these have been some of the most rewarding scenes for the group!