A typer rating and training to follow is a big investment for a company. While a business expense and tax deductible especially if it is a loss (Pilot leaving) the time put into an individual cannot be measured in money. Again in many cases companies taking deliveries of new aircraft are given a certain number of type rating slots and thus it is either an extra with zero cost or calculated in the aircraft purchase price. In the latter case the cost of the rating is assimilated by the book and or real value of the aircraft.
The above in mind a good company does not have to worry about losing employees and thus their bonds are short and usually a formality. Take the bad companies that keep losing people even during recession, these have training bonds extending to 5 years and additional bonding for company and line training.
Before it gets mentioned here. I have never heard of someone jumping a bond having problems getting hired elsewhere. Usually jumping a bond a result of a new job.