Touch and Go's / Carb Heat on Approach
The Continental engine on the C150 is very prone to icing, so I teach my students to leave Carb Heat Hot all the way down the approach to touchdown. The engine can ice up amazingly quickly, a matter of a few seconds and the last thing you want to be doing at 200 ft with not enough power to make the runway is having to re-apply carb heat and hope!
I accept the issues of having to go-around with less power and the fact that dirt and grit can damage the engine if you're landing on a bumpy or dusty strip somewhere, however I feel that in most cases a go-Around can be anticipated and simulataneously applying full throttle and carb heat cold in a C150 is very simple.
In the event of having to go around at the last second the C150 will happily climb awaywith carb heat hot.. and if you have been taught to always simultaneously apply carb heat cold as you apply full throttle you will have no problems with performance or the possibilty of engine failure due to a sudden rich cut.
Lastly I feel that the chances of engine icing and subsequent failure on approach are much greater and the risks therefore higher than that of a last second go around with reduced power.
For touch and Go's I teach
Flaps Up
Carb Heat Cold
Full Power
Of course, making sure you're keeping the aircraft straight and stable on the runway.
LP