As far as specialty grains, there is never any need to have 5 lbs in a 5 gallon batch. You'd have a huge muddening of flavors and it wouldn't work too well for you. You can though go for a partial mash.
If those specialty grains are Crystal malts, you'd have an awfully sweet beer at 3-5 lbs. If they're base grains (such as 2-row) that's fine in that quantity, but you'd need to do a proper mash, not a steep.