I wonder if the key common attribute for researchers is persistence. Not smarts or know-how, not project management skills or effective presentations. Persistence. If you don’t keep going when things are tough, if you don’t keep going when you reach a gap and need to learn (or jump!) then you’re stuck.
I’ve not met a researcher or graduate in the last decade who hasn’t had a problem of one sort or another during their PhD. Some of them severe. Yet they persisted. Kept going until the answer was found. Kept going until they saw a way forward. Kept going until they knew more or could do more.
The viva is the final bit of persistence. Continue to know you’ve done good work. Continue to remember you must be talented. Continue to believe you have all the skills and talents you need to meet the challenges of the viva.
Don’t stop now.