Honestly, you probably would, but how long it would take to get a tolerance depends on which one you take. Some like alprazolam (xanax) have a short half-life, and others like diazepam (valium) have a very long half life. If you use super short acting benzo's (small half life) and only dose once-twice a day, that day off might be enough time for all of the benzo to metabolize and get out of your system before you dose again. However, if its a long acting benzo (long half life), the levels of benzo will build up in your system.
For example, Valium has a crazy long half life, and some of its active metabolites have half lives of 100-200 hours. So if you took a dose of Valium this Tuesday morning, bu the time Thursday morning comes around, you'll still have a good bit of Valium in your bloodstream, so if you dose the same amount Thursday as you did Tuesday, you would have (Thursdays dose) + (Remains of Tuesdays dose)in your system. If you kept up that dosing schedule, you would have ever increasing blood levels of Valium over time, so you'd build up a tolerance to it even though you take the same dosage every time with days off.
The thing that sucks is that many don't realize this is happening until they stop using long enough for all of the benzo to be excreted from the system. They get the withdrawals and then find that the regular dose they take is not sufficient to relieve the withdrawal. They get tolerance to the drugs due to the ever increasing blood levels of the drug.