The simple answer is, you should strive to always use one program at a time for best results. If you do not choose to follow that advice, it becomes significantly more complicated, but I will try to keep it as simple as possible.

If you are using a 5th Generation program, you cannot use it with anything else. At all. Period.

For 4th Gen programs, a maximum of two at at time will be best. If you are using all 3rd Generation programs, you can try to use up to three at a time.

If you want to mix generations, follow these guidelines:

Nothing else with a 5G program. Mixing 3rd and 4th Gen programs, no more than two programs at once.

If English is not your first language, and/or you cannot speak it fluently, look at the scripts for the programs you want to use together. If you do not understand the whole thing, or one of them does not have a script listed, use only one at a time. Otherwise, proceed as if you do speak English fluently.

If English is your native language, or you can speak it fluently:

Please remember that there is no such thing as a free lunch, and it takes energy to make these programs work. You can't expect to use Stop Smoking, weight loss and hair regrowth all at once (all of these are programs that deal with making physical changes) and expect good results. Not because they don't work, but because you simply don't have sufficient energy and focus when using them all at once! Programs designed to manifest something, attract something into your life, or create a physical change (including dealing with an addiction of some sort) should be used by themselves if possible, and never with any other program of this type.

Using one attraction/manifestation/physical change program and one Type B at once is about the limit.

Just for reference...

Type A uses direct triggering of the lizard brain and currently only the Poetry of the Silent Eros uses this technique. You can use volumes 1 and 3 with other programs. Volumes 2, 4 and 5 should not be used with other programs.

Type B changes thoughts and beliefs to work. Up to two Type B programs may be used together, or one Type B and one program of another type.

Type C makes a physical change to the body. No more than one Type C or Type C hybrid program should be used at a time. Do not mix with Type C, Type C hybrids or Type D, or use with more than one Type B at a time.

Type D is attraction/manifestation. One Type D or Type D hybrid at a time, maximum. Do not mix with Type C, hybrids or Type D, or use with more than one Type B at a time.

Type E is long term programming. Become A Multi-Millionaire Within Four Years is an example. No more than one Type E program at a time. These programs require energy, and lots of it, but are also being used for very long periods of time. Use no more than two programs of Type B only with Type E programming. Type C, Type D and hybrids should be avoided. If you do use a Type C, Type D or hybrid program with a Type E, you should only use one such program at a time, with only the Type E reference program, and use the Type C/D/Hybrid for 2x as long.

Here are some examples to clarify.

I am using a Type E (BAMM) and I want to use a Type C/D Hybrid (Alpha set) too. I can do so ONLY if I use the Alpha set for twice as long (12 months for a 6 stage set). But, the instructions on Alpha Male say not to use it twice as long, so I would have to use it for six months at a time, twice. As in, one month per stage, and then repeat the whole set.

If I were using BAMM with something like a program to reverse hair loss, I could use the hair loss program for twice as long per stage.

If I was using Type B and Type E, I could use up to two Type B programs with it, as long as they were the only other programs I used.

And, regardless of anything else, if English is not your first language and you do not speak it fluently and do not fully understand all of the scripts for the programs you are interested in using, use only one at a time.

If you are using more than one program at a time, it is better to use each one for several hours straight and then switch to the other, than to loop them back to back. For instance, say I am using Alpha Male with Develop An Aura of Sexiness. The way to get the best results would be 8 hours of the first one, followed by 8 hours of the second one, and then 8 hours of time to rest. You'll have to use a playlist for this.
If English is NOT your first language - and you are NOT fluent in understanding spoken English - and/or you do not fully comprehend the published script for your chosen programs - DO NOT use more than one program at a time.