You most definitely can use carbide start to finish on pens. I have many customers who have told me the Magical Skew is the only tool they use.
On punky woods or plastics that like to chatter, you will find that you need a cutter not a scraper, so be careful what tool you choose.
Personally if the stock is 2x2 or smaller, I use carbide, if it is larger I start with a gouge.