For the Inset tool, I find that sometimes it won't give the option of adjusting the width for adding loopcuts and will aut...

For the Inset tool, I find that sometimes it won't give the option of adjusting the width for adding loopcuts and will automatically inset the faces selected by a certain amount. The last part isn't a problem since I can press control and adjust the inset, but not having the ability to adjust the width is quite annoying. Why does this happen? and how can I fix it?