If a revision is needed because the surgeon was cautious of removing too much tissue, It is not necessarily a bad thing.
It is an easy matter to remove a bit more. Attempting to fill a crater resulting from the removal of too much tissue is a different matter.
The problem comes down to the pre-operative assessment. Sometimes it is very difficult to distinguish between fatty and/or glandular tissue. Meaning that it is probably best to keep the surgeons options open to deal with what they actually find in the course of surgery.
When a patient agrees to Lipo only, The surgeon is handicapped by that limitation.