If you work on target compound quantification by GC-MS, then using single quadrupole systems is often a good choice, combining a very good price / performance ratio with capabilities of SIM and MIM. A quadrupole analysis method includes careful setup of transitions or selected ion grouping on the basis of retention time. As the suite gets larger, the method gets more complex and the sensitivity drops, eventually reaching point where the sample needs analysing multiple times. By contrast TOF looks at full mass range data with no loss in sensitivity, simplifying setup and keeping sensitivity. For example: single quad pesticide, SVOCs and aromatics methods can be combined into just one TOF method.