I have a 2 part answer to this one:
When I am away for work (2 out of 3 weeks) I shave almost every day with one straight, occasionally using a safety razor. I only keep one razor at work.
On my week at home I shave 3-5 times and either use one of my two other straights or (rarely) a safety razor, shavette or (aalmost never) my schick quattro (until the cartridges I have run out). I try to use the same straight for the whole week at home and change them from break to break as the mood takes me.