If you are doing "multiple steps", a State Machine (which uses a loop structure, with common values placed in Shift Registers and a Case Statement selecting which step you are doing, with one of the Shift Registers usually serving as "Which Step is Next?" decision) makes sense, and also has the side benefit of taking a long strung-out Block Diagram and "stacking" it in a "natural" structure.
On the other hand, some use the Sequence structure to (... pause ...) control the sequence of the VIs/functions involved. In many cases, a better way to sequence things is to use the Principle of Data Flow, which often means The Error Line Is There for a Reason -- Use It. Note that most NI functions have Error In and Error Out terminals, and NI Best Practices recommends that you use a 4-2-2-4 Connnector Pattern for your sub-VIs, with Error In and Error Out in the lower corners. Functions place on the Error Line with (by the Principle of Data Flow) execute in the order they appear on the Error Line.
One of the few times that a Frame Sequence is required is if you need a 100-msec delay between one function finishing and the next one starting: the Wait function doesn't have an Error Line, so when I need this, I either use a sub-VI I write that includes the Error Lines and a Wait inside, or use a Frame Sequence to surround the Wait and make sure "An Error Line Runs Through It". [My apologies to those who may not catch the bad pun there ...].
Bob Schor
