Can given crankset have limit on spindle width?
You are taking the right approach to figuring your chainline per a given spindle, but yes, there can be other limiting factors.
If you go too far, it is possible for the crank body near the spindle interface to smack into the bottom bracket shell or the cartridge body, or be low-clearance enough that flex and grit wear a groove into the crank. Low-profile cranks increase the likelihood of this. Using something like a Phil BB that has zero protrusion from the shell can avoid the problem where a Shimano or similar will run into it, which can be useful if you absolutely need a certain spindle length.
The above is not super common, but you can get it to happen in some situations. I've seen it mostly when putting 135mm-oriented era touring triples, i.e. the Sugino XD600 and XD300, on bikes with older chainline numbers or when trying to get the Q minimized. I think I've seen it at least once when someone was configuring a road crank for track chainline with the ring in the clean-looking outer position.
Interference between the ring(s) or spider and the frame is also possible.