Poppy,
Just a further thought on limited panal turns. I thought about the alternative of timed v using the mag compass whilst flying yesterday.
As you know, IO540 and myself came out strongly for the timed method.
You have no direct information on angle of bank (or pitch). To fly reasonably accurately requires constant attention to the remaining primary instruments. The standard layout puts the TC at the lower left, and the ASI above it, with the Alt to the right of the blanked off AI.
The mag compass is to your right, above all other instruments, and often, as in my aircraft, roof mounted. It is outside the field of view when flying on the primary instruments. In short, you cannot see the TC and the mag compass at the same time. The more you turn your head to follow the mag compass, with all its wobbles in turbulence, as well as the previous mentioned errors, the less accurately you will be flying the aircraft in maintaining rate of turn and altitude. The timed method obviously only works if you retain the rate one turn accurately, but this I have always found easy if the mag compass is totally ignored until it will have settled 10 secs after levelling out.
In my aircraft, and I think most, the clock is within the field of view of the primaries, and I don't bother with the stopwatch. My examiners, in all the multitude of renewal tests I have taken, have normally asked for 60deg or 90 deg turns, ie 20 or 30 secs, not 20 deg which as IO says can be done simply by counting to youself. I wouldn't trust myself to count to these longer times. But given the instruction on the heading to finish on, you can always take a few seconds to know the time required, decide clock positions of the second hand for start and finish times, and start and finish the turn accordingly. As IO says, it really does work, provided you attend to keeping the TC on the rate one mark, and don't take sneaking glances at the mag compass.
It means being well practiced in simply maintaining the rate one turn, before expecting accuracy in turns to a new compass heading. Certainly for me it means that I can maintain much better altitude accuracy than if ones eyes are moving to the mag compass during the turn.
Whilst the test gives wider tolerances on accuracy when on limited panel, I have always set myself the achievement of the same tolerances of full panel flying, and really do not think I could do this if I attended to the mag compas during the turn. (And whilst I'm IMC rated, I also set myself the IR tolerances.)
Just a thought.