The early schiltrons formation I agree where of circular and static type(battle of Falkirk ,main battle of Bannockburn for example) but schiltons become rectilinear during the 14th century and where used for both attacking and defensive work.
If the schiltron developed from the shield wall (shield wall formations exist in the early scots medieval lists, even for normal spearmen) I find it odd there is no reference to any formation, shield wall or otherwise in the medieval list (the scots appear to have abandoned all formations for the next 250 years
) . The fact is the medieval scots did have early pike formations at the least from 1300AD and these should be included into the later part of the medieval list. A work around I have been using to play a schilton formation ,is the phalanx rule, with the of exception of they do not get the shield wall bonus against missile fire.(and of course don't get the trained ability to ignore the drift or combine units ) this seems to work ok and restores a vital factor to the scots medieval army .(I would like to hear what you think on this work around) Thanks. I use the basic "pike men" cost from the scots renaissance list, might be a bit pricey points wise however .