if you do the math (dealer chooses randomly unless it's the last one) then in any case where neither of you have items and the shotgun has one live and up to four blanks, it is still better to take that 1/5 chance of shooting the dealer, because they are always equally likely to shoot either you or themselves, and you mostly only care about them giving a loaded gun back to you, ideally one that they might accidentally shoot themselves with after you attempt to shoot them again. (of course, with items it gets more complicated and sensible, but sometimes it's better to try and waste a bullet on yourself if you have bad items, just so the dealer doesn't hit you with double damage)
I also just want to mention that it's always better to shoot the other on the last round because skipped turns don't carry over after items, and the player always gets the first turn.