start brush stroke where I just stopped

Do you have Lazy Nezumi Pro?  If you are using Windows and have a tablet, then LNP is the biggest no brainer Photoshop add-on bar none.  You can set whether the next line starts at the start, centre or end of the previous line, or you can toggle between those using the Shift key.

LNP has a zillion different presets like this, and a lot of them work just as well with a mouse.  Unfortunately, we are told there will never be a Mac version.  You can try it for 15 days before committing your $30.  I think it's $13 a year to  keep getting updates, and there are a LOT of updates.   The preset I use the most (appart from Masive Smoothing) are the perspective aids.  It makes drawing so much easier, and accurate.

https://lazynezumi.com/

[EDIT]

I thought I'd add that because of the imense number of LNP preset options, it can be a matter of finding 'wood for the trees', so a wee tip is to use the LNP toolbar.  That makes it much easier to find and select particular functions.  I've outlined the Connected Lines icon. 

You could do it like this: After your initial stroke, position your cursor at the end of the initial stroke, and Shift+Click to start a continuation, but release the mouse before dragging it to paint.