All withdrawals from 3a and second pillars are taxed on total sum. You can have as many portfolios as you want, but at least 5 is recommended.
How old are you?
No 
.
You can open different portfolios to implement different strategies, but itâs a different story.
That would mean there is no benefit by having more than five 3a portfolios alone provided somebody retires at 65?
30, came to Switzerland fairly recently.
I hope I am correct that it wonât matter if portfolio 1 would have e.g., MSCI quality and then I would add an Ex-US stock or I would open portfolio 2 for Ex-US?
Yes. And I havenât mentioned that withdrawals by spouses also add up. At least with the current taxation practice.
Anyway, you can always merge 3a portfolios, but it is difficult to split them.
This is 3a provider specific. With finpension I am trying to have one fund per portfolio, make things easier.
Therefore you still have 200-250 kCHF to contribute. Too early to worry about the size of portfolios with respect to the staggered withdrawals.
More balanced would be to rotate every year. But with 10k, I wouldnât bother with various accounts, yet, let alone different portfolios. You could do that, of course. Itâs also fairly simple to change the strategy within a single account.
If you plan to buy-in for the next 30 years, it wonât really matter whether you add your next accounts now or once you hit a certain amount in the first one.
Aside from that, maybe check your local taxes to understand how steep the curve is. In ZH it doesnât make a huge difference as long as the withdrawals are 5 digits.
I guess more accounts gives you more flexibility. Iâd put into a different one each year.
You can also split your monthly payment into the 5 third pillars so they will grow equally.