When working with multiple branches and worktrees, the commit log often gets very crowded. Thus, one frequently has to scroll for a long time to find the next related parent or child commit of the currently selected one.
SmartGit, for example, has nifty shortcuts to circumvent this problem. You can press Alt + Up/Down to jump to the child/parent commit from the currently selected commit. If there is a fork, i.e. because of a merge, a small popup is shown where you can select which of the paths to follow.
In the following example, I pressed Alt + Down to go to the next parent commit and get to choose which one to go to, as there is a fork because of a merge commit:
I would love to see this feature in SourceGit as I dearly miss it after switching over from SmartGit.