15 - 45 minuten
The stock battery in my daughter's iPhone 5c was SHOT. She's a heavy user, producing video content frequently. Her phone would show 30% charge, and just die.
The new battery from iFixit went in as "easily" as it could have. (Thanks to plenty of old battery adhesive.) And of course, iFixit's care package had EVERYTHING I needed to get the repair done perfectly.
Use the heat source (iOpener) patiently. If you think you need more- USE MORE. Adhesive gives way to heat, but you've gotta use it to avoid damaging components.