1. Not heard the rule of not opening 1nt with a useless doubleton in a major but Im sure a variation of it exists - you'll have to ask leo.

 

2. Some people will open 5/5 in the blacks because it is easier to introduce spades at a higher level than introduce clubs

 

For example 1c-1h-pass-2h-2s would instead be... 1s-2h-pass-3h-?

or similar for 1c-1h-pass-3h(preemptive)-3s 

 

This method isn't followed by everyone.

 

dont remember leo saying not to open 1nt if  hand balanced.15-17.

He may have said dont open 1nt with a 5 card major and a useless dbltn in the other major.  Open  the 5 card major.

that he did say.

1) I am not sure what Leo said, but I open all balanced 15-17 HCP w/o 5 card major with 1N and all balanced 20-21 with 2N. I don't worry about stoppers or weak doubletons. AKxx/xx/AKQx/xxx is a 1N opener. AKQJ/xx/AKQJ/xxx is a 2N opener. This is the modern style.

 

2) I open all black 5-5 with 1S, but not all agree with me. The reasons I do it:

Prior,

 

It is my habit to open 5-5 black hands with 1C. Of course, my partners do NOT bid 3NT as in your example, We play fourth suit forcing to game, so there is no need to jump that way. Anyway, a few months ago, I was challenged about my preference of 1C with 5-5, and I have kept track, Of the 10 times I have opened 1C, all have worked out successfully. Why fix something that is not broken? (Not being difficult here, but truly inquiring!)

 

Steve

If you are 5,5 in the black suits it is best to open 1 Spade if weak (get the major suit in quick) and 1 Club if strong.  In this way you can always subsequent ly show your spades

Leooooooooooooooooooooo

Leo explains it well  ,,,, reasoning is   just the opposite of  what  grandslamz  is  saying  with the weak hand   open 1 cl   so you can bid and rebid  spades   at a lower  level  with a stronger hand you will have time to show the  5 crd club suit

In Steve Robinson's book, "Washington Standard", he said to open 1S with

xxxxx - - AKQJxxxx

 

I figure if a world champion can open 1S with that, then I can open 1S with a black 5-5.

 

I have in the past opened most 5-5 black hands 1c weaker and opened 1s stronger hand in order to get both suits described at 2 level. I believe this has worked well for me most often. However, with so many modern conventions that show major suit raises such as multi 2nt, bergen raises,  jac2nt, BROMAD, game forcing limit raises, splinters , minislinters, fitbids, etc, I HAVE DECIDED TO OPEN MOST HANDS WITH 1M. I want to use these conventions. When they help, that's my fun.