Autocoding of large amounts of job expenses from SA return

Our clients often have single year's claims of S.336 "job expenses" under SA.  We always complete the additional info box stating the expenses are unique to that year and not to be coded, but now they always are, due to Autocoding.  This is all very well for small amounts of FRE, but for four figure sums automatic coding is plain daft, leaving clients with massive underpayments at year end.  Why no opt out box, as with gift aid, to keep the claim in the year?  Apparently the returns are processed and the white box read at a later date - what good is that?