By adjusting the combustion process and therefore improving combustion efficiency one ultimately saves fuel.
Although some combustion experts do weekly tests others consider three or four checks a year an acceptable level of testing. The appropriate level for a particular unit can only be determined by experience, and is partly dependent on the fuel consumption of the burner. The higher the consumption, the more important it is to optimise the process. Fuel consumption will be affected by a number of factors that can be measured with a flue gas analyser. The air/fuel ratio is an obvious candidate, together with the pressure drop in the stack. The carbon monoxide produced and a few other factors all add up together to change the efficiency of the burner. What works at low load my not work so well at full or half load.
It is relatively easy to work out a programme of testing frequency. It is common to start with frequent testing and find the rate of change of the process. Testing will be necessary after any major changes, such as a differnet fuel type or large-scale maintenance work. It is omportant to get an idea of the performance of the burner at different levels of load and varying fuel composition (if applicable). This will make it fairly simple to work out a plan for optimal testing, without unnecesary use of manpower.
The stability of the combustion process is perhaps the biggest factor here: a stable combustion process will require less testing than a system where constant changes are being made. Fuel savings are possible with both systems, perhaps more with unstable processes, since there may be factors that make the combustion process much less than ideal under certain circumstances. Fuel savings will depend to a great deal on discovering these conditions and either avoiding them or changing the combustion process to take account of them. In point of fact, these unstable conditions give the biggest potential for fuel savings, since they may be a long way from the ideal state.
In countries with large differences in relative humidity and other factors, these must be taken into account when testing. These can have a large effect on fuel consumption and hence provide the potential for large fuel savings. In general, fuel savings are always theoretically possible and can be realised in most cases. There may be certain cases where the efficiency of the combustion process is secondary to another factor, such as a requirement for a reducing atmosphere, or a necessity to keep the stack temperature above the dewpoint for a certain component, but, even in these cases, it is often possible to achieve a small but noticeable fuel saving.
As can be seen from the discussion above, this question is not easy to answer. The best answer is perhaps, yes, but is it worth it? As fuel prices rise it will become more and more worthwhile to take advantage of any chance to save fuel. It is also not just a question of money. Fuel is an import commodity and is limited in supply. When it has been used up, there is no more. At the moment we still have a reasonable amount available, but there is no real sign of new technology to replace the present fossil fuels. This would imply that we should save as much as possible or risk the consequences.
It is also not in the interest of many countries to be dependent on imports of fuel or other materials any more than is strictly necessary. The potential for political blackmail in this branch was amply demonstrated in the 1970s with the oil crisis paralysing an unprepared Europe. Hopefully, the lesson has been learnt, but reserve stocks of fuels are still very low in many countries. Fuel saving will reduce this dependence and free resources to combat other internal problems. The potential is there and need not be very expensive or complicated at first.