Ithink we need to remember that every hospital, unit, physician, location in the country....all have their own feelings about which drip to use when. It is really patient, facility, and physician preference as to what to titrate and when.
Check your facilities policy and procedure manual. Know you units specific standard of care. There should be a drug book policy on your unit or computer.
The actual titration is based on patient response. You start at small increments and increase more or less rapidly depending on the patient vitals and response. What one patient may not be responding to and will need titration at 5 or 6 mcgs at a time....another patient will have rebound tachycardia and HTN with as little as 1-2 mcg.
It comes in time and experience....I know when I started out in ICCU I depended ALOT on the senior nurses (10+y) to show me the tricks of the trade...it's a shame that learning model is no longer used and the older nurses are no longer considered valuable.
Here is a good rule of thumb....http://workplacenurses.com/id69.html
you might also find this site helpful...icufaqs.org