To work out rough estimate of height vs distance if short cuts are the norm,try PF CDU LEGS page,PM CDU PROGRESS PAGE and note current distance and estimated FMC heights,then join short cut but do not excecute,the PROGRESS PAGE will come up with distance gained then divide by 3 and put that height/speed reduction at the point where you think the short cut might occur,this will give you the vertical deviation and work form there.
And always have Smokey's '''gentle meander' around the direct track, weave, Roll and pull, roll and pull............. land, that's a good summary of descriptions of my normal approach technique, what do I do if I need to steepen the approach'' method ready.