[QUOTE] Another example is if there is variable wind. One could want to fine tune heading bug degree per degree according to the wind to account for the drift angle as precisely as possible.
But obviously, asking the PM "two degrees left, no one degree right, etc.." would be too much time consuming (whereas adjusting heading bug alone in a single pilot operation is just the normal way of doing things and very easy), so you end up asking "set runway heading" and visualise a drift on the PFD. [/QUOTE]
Why would you do it in HDG? TRK can save you all this unnecessary fiddle. If you speak drift, that by default means that you are following a track, not a heading. The A320 can self-correct appropriately for any wind in TRK mode.
As for manual flying, it is indeed important (and also quite enjoyable) to practice your handling skills frequently. The actual motor skills required to fly an A320 in normal law are not exactly impressive; however, having the correct distribution of attention and maintaining good situational awareness while flying manually can only be trained by actually flying manually. So, I'm not buying the opinion of some colleagues that the entire exercise of manual flight is useless "because it pretty much flies itself". It's important - however, it has to be done in the right way.
First, ask yourself whether the situation is appropriate. It's not the best idea to fly manually for extended periods of time in busy airspace with a lot of traffic and busy ATC, in poor weather, while being tired etc. However, if it's a reasonably nice day somewhere not too busy and you are both feeling alright - the next step is to agree on a common plan how to do it. Most of the people I have flown it by default assume that the AP will be engaged by about 1000 ft AGL on takeoff and disengaged somewhere below 1000 ft AGL on landing. So, if you want to fly manually up until FL100 - ask your Captain if he would mind it. Similarly, if you just want to disengage the AP a bit early on a standard ILS - just ask if it's OK to do so. However, if you want to do a raw-data ILS in manual flight, there are also some additional items you need to include in your briefing. This one is usually an early stabilised approach instead of a decelerated one - which needs to be briefed. Some companies prohibit combining raw-data flying with manual thrust, so be on top of your OM-B. Also, on some old aircraft the FDs will not engage automatically when setting TOGA on a missed approach - and that needs to be mentioned in the briefing as well.
So, in a nutshell, the safety rules are - assess whether the situation is suitable for manual flying, agree on a common plan with the other crew member, assess and brief appropriately any peculiarities. As long as you do that and don't violate anything written in the books, you should be fine.