Love it or hate it, it will give you a headache.
I think the most apt description I’ve ever found for time are a combination of Quantum Leap which relies on the string theory that time is like a ball of yarn and you can jump from one to the other, and Doctor Who where time is a wibbly-wobbly, timey-wimey ball of stuff, which really sums it up nicely and succinctly.
I thought there were many more time travel episodes in the Supernatural universe, and I could only remember about five. The rest that were in my head were more of flashbacks, which aren’t time travel per se, but in doing my research in the Supernatural wiki, I saw that they counted twelve, which I will list here even though there are a couple that I didn’t particularly consider them for my personal list. For example, in As Time Goes By, Henry Winchester travels forward from 1958 to 2013 and in Lebanon John Winchester travels to current day Kansas despite his being dead canonically. I was looking for the episodes where the brothers traveled through time.
At any rate, these all have something to love, and yes, they will still give you a headache.
1. In the Beginning [4.03]
2. The End [5.04]
3. The Song Remains the Same [5.13]
4. My Heart Will Go On [6.17]
5. Frontierland [6.18]
6. The Man Who Would Be King [6.20]
7. Time After Time [7.12]
8. As Time Goes By [8.12]
9. King of the Damned [9.21]
10. The Vessel [11.14]
11. Family Feud [12.13]
12. Lebanon [14.13]