If you were an aid of Alexander the Great, would you have advised him to expand his empire as much as he di?

yes cause thats the only reason you're talking about him now and know who he is, or else he wouldnt have been great.

Probably not, while occupying a lot of territory seems great, problems arise from doing so.

1) Occupation of enemy territory requires you to maintain a military presence in the area to keep it, the more area you occupy, the large military you need otherwise you risk being spread too thin and having to deal with civil unrest.

2) Large expansion can cause you to face things such as diseases that you're not used to. While far away from their home, the soldiers could encounter diseases that their immune systems never faced. Simple diseases can prove fatal against unprepared immune systems, so when the soldiers go home, the diseases spread among the populace.

3) Conquering large amounts of territory can cause undue attention from otherwise neutral nations. If they start questioning what is stopping you from invading their country when they're done with you, they may offer assistance in reclaiming the countries lands, so now you're facing multiple allies at once unified against you instead of one opponent on their own.