Sometimes less is more. More can lead to confusion.
To be specific, I think if you had brought up just the issue about the “negative corner” without the digression about the angles of the bits, then I wouldn’t have been confused.
That in fact is the base design. The panelised version was put together using the Append Board feature of pcbnew.
The crazy thing about typical pricing is that it would be cheaper to send in an order for the base design instead of letting them charge for panelising 1x2, even if half the number boards are ordered. The drawback is of course the appearance.
I know professional production uses panelising for other reasons, such as faster assembly.
I think this is what Jan-Ake meant by two cuts. But the minimum separation of cuts appears to be 5 mm so that much of the board will be wasted. I’m a cheapskate trying to cram stuff into the magical limit of 100x100 mm cheap boards.
I could also give up rounded corners, but I prefer a slight asymmetry to being poked by sharp corners in handling.
It looks like we all have now understood what’s going on. You can send your order, then take some photos and show us what it looks like when it arrives.
Will do. I’d like to see if my prediction is true.
Yes, correct. I meant leaving an empty strip between the two boards.
In my case I have the vertical edges of the boards milled, and the horizontal edges V-cut, using a pcb strip above and below the boards to give stability.
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Not necessarily, and this didn’t used to be the case at all.
The original way of v-scoring was to put the board through a separate machine that would feed the board through a pair of rotary cutters that would vscore both the top and the bottom at the same time. These machines couldn’t easily start and/or stop the vscore in the middle of a panel (either the manufacturing panel or a customer’s panel) so the manufacturers wouldn’t allow specifying stopping a vscore part way through a panel. (This is why many vscores continue across the breakaway strips on either side of a customer panel laid out for PnP handling.)
Maybe some board manufacturers have started using pointed mills for vscoring, but that means that the manufacturer needs to be able to properly index the panel in both top up and top down orientations on the milling machine.
Back to the point of laying out a panel for PnP assembly lines, often it is advised against using vscores parallel to the handling strips on the sides, especially towards the middle of the panel because of the downward forces from the part placement heads during the PnP process. The vscores are weak areas where the board might actually break during PnP ruining the panel, placed components, and making a right-mess in the PnP machine that the PnP technicians will need to halt production to clean up. Keep your vendors (or in-house departments) happy by not designing in potential issues. 
Yep. When designing it is very important to know the capabilities and limitations of your manufacturer and assembly service. Ask first. Several times. Are you sure?
In my experience, they don’t allow such a trick but will charge you extra. Or perhaps that was because I had two different boards on the same < 100x100 panel? (Two boards part of the same design, meant to be sandwiched together)
I was able to submit two instances of one design using slots, breaktabs and mouse bites for no extra last time. This is allowed by their rules. https://support.jlcpcb.com/article/49-pcb-panelization first Note:. This doesn’t cover your two design board.
This time I’m trying another fab that offers free V-cuts, with the usual restrictions on position, size of board, etc.
I reckon that JLCBPB generally give you boards that roughly add up to the total surface area. In the past I have submitted an order for five boards about 4cm x 8xm and received 10 and also got 18 (I think) of something around 5cm^2.
They are happy to process a self-panellised board and don’t charge extra unless the two boards are different. Annoyingly, this means that an alignment rail counts as two different boards - however, I think the criteria that they use to determine if it is one or two boards is to see if there are traces that run through the mouse bites. Two electrically isolated boards counts as two boards but two boards with a trace across a mouse bite counts seems to count as one board and you are OK. YMMV
Right. So does JLCPCB charge extra for multiple boards of same design, separated by V-cuts? Sounds like it should not cost extra reading your above link.
Clever. I’ll try that trick next time! 
My last order fit on half a board so I duplicated it and did a vscore. Now I have 19 more boards that I need.
I think what happens is that they fit small boards in the margins of larger jobs that don’t fill the sheet. So you got 10 boards because there wasn’t a 5 large board job to piggyback onto.
Sometimes you get 11 instead of 10, 1 just in case.
I didn’t put a trace across the mouse bite and it went through. So it may depend on visual inspection and sometimes they don’t call out multiple design boards, as some people report getting them through.
Except there is no way in the form to state that it’s customer panelised with V-cuts. Maybe you have to contact them and tell them which is the cut layer. With slots you don’t have to state anything.
JLCPCB says to put v-cuts as a line from board edge to edge, on the edge cuts layer.
Is that what they said? And they will deduce it from the position of the cut, no need to add a note? Thanks, that’s useful to know.
Yes, I emailed them and got this reply:
Thanks for your e-mail, for the V-cut line and cutouts , could you kindly to make them on the outline layer (GKO=Profile=Outline layer)?
Ok, I have received my boards from LocoPCB and it’s more or less what I expected. My Hackaday review has the details, but for the V-cut feature, this is what I got:
The ledge is wider than I expected because the V was more acute than the 30° or 45° I was expecting. The ledge is the price for wanting rounded corners. To avoid this I’d have to use a rail between two V-cuts, sacrificing some board area.
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