Stardew Valley non-gamer: Catch fish and level up without playing the minigame
Channel: Tom Haws
Date: 2022-01-18

I demonstrate an all-day test of buying the Training Rod and fishing with it without playing the minigame. In other words, I don't move the green bar.

Conclusion (including results of previous tests): 
You can usually reach fishing level 2 on the first day fishing with the Training Rod without playing the minigame. If you are not reaching level 2 in one day, try not playing the minigame.

Detail:
Cast time and result
9.08a Lost
9.44a Trash
10.11 Sardine perfect, Level 1 (mostly from pre-test Sunfish, Halibut, Sardine, and Flounder; 4 fish)
10.46a Sardine perfect
11.00a Lost
11.30a Seaweed
11.46a Lost
12.16p Seaweed
12.50p Lost
1.18p Seaweed
1.33p Lost
1.47p Herring
2.18p Herring perfect 
2.41p Seaweed
3.09p Lost
3.23p Lost
3.35p Sardine
3.50p Sardine
3.58p Herring perfect
4.15p Lost
4.47p Moved to bubbles
4.48p Seaweed
4.52p Lost
5.00p Miscast
5.03p Sardine perfect
5.12p Lost
5.22p Miscast
5.38p Seaweed
5.46p Lost
5.57p Missed bite
6.03p Lost
6.12p Lost
6.21p Lost
6.29p Miscast
6.33p Herring perfect
6.50p Seaweed
6.59p Miscast
7.03p Seaweed
7.10p Driftwood
7.21p Herring perfect
7.31p Broken glasses
7.39p Driftwood
7.51p Lost
8.00p Lost
8.14p Lost
8.26p Anchovy
8.40p Broken glasses
8.52p Lost
9.05p Herring
9.13p Lost
9.25p Seaweed
9.34p Soggy Newspaper, Level 2
9.46p Lost
9.52p Anchovy
9.59p Lost
10.11p Herring
10.21p Seaweed
10.28p Anchovy
10.41p Seaweed
10.47p Broken glasses
10.55p Trash
11.02p Seaweed
11.12p Herring
11.18p Soggy Newspaper
11.26p Lost
11.40p Herring perfect
11.49p Seaweed
12.17a Broken glasses
12.50a Herring perfect
1.09a Broken CD
1.26a Seaweed
1.41p Seaweed
1.54p Lost
Ended around level 2.15 +/-

Training Rod advantages:
1. It's cheap (25 gp).
2. "[I]t sets the player's fishing skill equal to level 5 for the purposes of determining how big to make the green bar (136 pixels)." (Official Wiki)
3. It saves backpack space by preventing quality star fish.
4. It saves time by preventing difficult fish you can't catch.
5. It saves time by removing any reason to cast any longer than the bare minimum.

Training Rod disadvantages:
1. It limits income by preventing quality stars and difficult fish.
2. Like the Bamboo Rod, it does not allow bait that increases bite rate.