Same. At least for The PC.
Later machines were of course throttled accordingly to keep slot access speed within the original spec. What else should they have done?
But they tried, and from there on it gets complicated.
The PC-AT did run 1 wait state on each 16 bit access, IO or memory, internal or card. Thus allowing 'full speed'. But it inserted 4 wait states for any 8 bit card access - working as a slowdown to even a little less than PC speed, making sure 'old' 8 bit cards would comply.
This was done by the card pulling IO16 or M16 whenever it decoded an address as theirs and 'decided' to support 16 bit access - or better one should say fast access, as this of course also worked with any access, 8 or 16, as long as IO16/M16 was pulled during the initial clock cycle. A 'real' 16 bit access (reading or writing a word) would, without O16/M16 pulled, be split into two 8 bit accesses by the PC glue logic, each with its own 4 wait states.
This way a 16 bit memory expansion could work at full speed, while 8 bit I/O cards worked at a PC-like access timing.
To make things even more complicated, NOWS (NO Wait State) pulled during the middle of any access cycle would stop the wait state generation with that cycle (*1). Alternatively CHRDY (CHanel ReaDY) could be used to extend wait state generation as long as needed (*2,3).
And somewhat related, there were also what I would call 'virtual' 16 bit cards. Most notably here some of the first faster VGA clones. They were usually sold as 16 Bit VGA, but in reality they were 8 bit designs. After all, the original VGA is an 8 bit design, and so were (most) compatibles. The trick here was to implement the byte/word glue logic onto the card. A write access was always accepted with IO16/M16, just to be handed toward the controller as two 8 bit transfers - while the 80286 continued its duty. On a read the wait state was used to fetch both bytes from the card.
Of course there were also real 16 bit VGA cards later on. But those were newer controllers and designs.
Oh, and then there's the case of mixed display adaptors. As soon as there is one 8 bit display adaptor in a system all will be accessed as 8 bit. Thus mixing one of the nice 'virtual' 16 Bit VGA with an MDA will pull the VGA down to PC speed again - unless it also used NOWS that is, then it's only slowed to 8 bit speed.
*1 - So an 8 bit cycle could be cut short at the first, second or third cycle as well.
*2 - Both signals were already available with the PC.
*3 - Pulling both created an undefined state.