I managed to do it in 28 days all said and done. How? By skipping about 1/2 to 2/3'rds of the captured locations and pushing on the palace. Even by beating the game this way I still got the "poor ending" with the bio weapon attack occurring.
So aye, it seems they expect you to either skip a good portion of the content or put up with angry mail from your employer who's upset you can't quite manage to liberate an entire country in 30 days with just enough cash to afford a new Volvo C70.
What would have been cool is after the 30 day mark he contacted you with an extra payment for an extended mercenary contract and thanked you for fighting so hard to liberate his people.
Or better yet, a special side quest to defend one of the cities you've already freed against a small siege/assault by his wife's forces while he pays his people a visit and rallies them to the cause. ViVA LA RESISTANCE!
Just something to mark the rough midway point of the campaign rather then demoralizing spam from your employer. (Hmm maybe that;s why his wife tried to have him assassinated all those years ago? He kept having unrealistic expectations of her capabilities around the palace? )
To be fair the C70 is a really good car, though you are talking to someone who owns an ex British Army Land Rover that cost under 5k lol
The best way to stop the emails like in the original JA2, is that you go and attack or defend a Sector every couple of days, I guess the idea of the Email system is to provoke you into action as I'm sure in the real world, Mercs have been called in and switched sides or been worse than the current occupying forces/rebels in some African nations so maybe its Enrico having his doubts about you ?
If you're hired to go do a job, you keep on the attack not sit on your laurels enjoying the profits of Mine income despite you're meant to go oust a Dictator ? lol