If it weren't for Dresden's superhuman regeneration, I'm fairly certain he would probably be in a coma from all of the times he's blacked out in the series. To be specific, he's blacked out at least once in almost every single book

Storm Front: fainted after his battle with Victor Sells

Fool Moon: bludgeoned by the berserkers and tied up

Grave Peril: knocked unconscious by all of the Red Court Vampires and taken captive

Summer Knight: blindsided by Elaine and Aurora's group

Death Masks: pistol whipped by Nicodemus and taken captive

Blood Rites: collapses from exhaustion and pain after getting his arm burned and after fighting the Blampires with Thomas and Lara

Dead Beat: pistol whipped by Cowl to prevent the capture of the Erlking

Proven Guilty: knocked out by Madrigal Raith and his sidekick and (surprise surprise) taken captive

White Night: briefly loses consciousness after being shot at by Madrigal Raith

Small Favor: collapses from exhaustion and the cold after picking up the Archive, blacks out after almost drowning from the burst Aquarium

Turn Coat: blacks out multiple times while trying to desensitize himself to viewing the Naagloshii with his Sight

Changes: faints after the use of Chichen Itza's sacrificial alter

Ghost Story: wasn't alive, doesn't count

Cold Days: I believe he faints from the nails and attacks that Ace's Little Folk use on him, but I could be wrong

Skin Game: Dresden faints at least twice (possibly a third time, can't remember off the top of my head). Once with the Genoskwa attack, and another when he's about to give birth

So, it's pretty obvious that Dresden falls unconscious quite a bit, almost once each book. I wonder if that'll change in the future

Edit: fixed a word

Edit II: added Turn Coat black outs thanks to /u/Apairoftits