The board house will tell you if they have issues.
If the perforation drill holes (center/center) aren’t closer than 2 diameters, they shouldn’t have any problem.
Also, sub-boards might incur an extra fee per board, depending on the board house for the extra milling I guess?
Don’t reduce the space between sub-boards to less than what the board house is able to mill.. 1mm router bits are the small end of the scale, bigger is better here (I’ve done 1mm for last 4 boards and no problem).
The tab width and distance between tabs influences mechanical stability.. I’m still impressed by the stiffness that 3mm wide tabs with 3x 0.5mm drill holes at a spacing of ~50mm create between sub-boards.
Also: