Heavy use of the autopilot is not a problem. Reliance on the autopilot
is absolutely deadly unless you have multiply redundant autopilots with
redundant power sources. There's no problem in using the autopilot as
long as you're also getting plenty of time in the equivalent flight
conditions and are very comfortable in them. Basically, it's OK to use
the autopilot any time you would allow a child with emotional problems
who is good at playing flight simulator to fly the plane while you
watch. The degree of monitoring you should exercise should also be the
same.

Most pilots already get plenty of experience flying day-VMC in cruise,
so using the autopilot in those conditions is no big deal, just as it
would be no big deal to let any passenger fly under those conditions.
If you're one of those rare people who gets plenty of actual all the
time and feel very comfortable in the soup, there's no issue with using
it in the soup either. If you shoot so many approaches to minimums in
actual that you find the process boring, it's fine to let the autopilot
shoot the approach.

If you are struggling to get enough actual to stay proficient, and even
going under the hood, then why would you give any of that valuable IMC
time away to the autopilot? You need that time to keep your skills
sharp and hopefully develop them. You're paying for that time.

Realize that no GA autopilot on the market has the capability to
crosscheck gyros. Any of them can cause the ailerons to go to full
deflection smoothly but quickly. As long as you're always in a
position where you are confident you can recover from that safely,
there's no problem with using the autopilot. If you're in a position
where that's not true, why are you there?

If the reason is because you can't handle the workload (or are not
confident you can handle the workload), fine, turn on the autopilot.
Then make it a point to get more training/practice prior to your next
IMC flight. Otherwise, all you're doing is increasing the risk.

Personally, other than in training, I use the autopilot only in level
crusie in VMC, generally on long trips so I can rest. I never use it
in IMC because I don't feel like I get enough of it to stay sharp (I go
under the hood at least once a year for recurrent) so I'm not going to
give any away to the autopilot. If I ever feel like I'm losing it,
I'll turn it on. If I had to fly several hours of solid IMC in one day
single pilot, I would use it in level cruise, to reduce fatigue and
keep myself shart for the higher workload terminal and approach
operations.

Of course everything I said above is based on the idea of the
proficient pilot - someone who could easily pass his instrument
checkride in whatever plane he normally flies IFR without needing to
prepare for it. This does not describe most instrument rated private
pilots I've met. I suspect that has a lot to do with the abysmal
safety record of private IMC flight. I've only ever met a few who fit
this description, and most of them, even if they don't fly
professionally, hold professional ratings. The average instrument
rated private pilot I've met was probably at his best as an instrument
pilot the day he took his IFR checkride, and would need to practice
quite a bit to pass it again. For someone like that, I recommend
buying the best, most modern autopilot he can afford and using the it
as much as possible throughout the flight, since the autopilot is less
likely to screw up than he is - that is assuming he is not willing to
practice enough to bring his skills up to par and is unwilling to give
up flying IFR, both of which I consider better options.

Michael