Updating massive amount of rows whilst avoiding blocking

The following SQL is a good means to split an update on a massive table into smaller chunks, whilst reducing blocking. The method is to update top N rows from a table, within a while loop, with a wait between loops, to avoid excessive blocking of the table and allow other transactions between each loop. Further blocking reduction is discussed in the link below.

set nocount on

declare 
    @ChunkSize              int = 1000,                         -- count rows to remove in 1 chunk 
    @TimeBetweenChunks      char(8) = '00:00:01',               -- interval between chunks
    
    @Start                  datetime,
    @End                    datetime,
    @Diff                   int,
    
    @MessageText            varchar(500),
    
    @counter                int = 1,
    @RowCount               int = 1,
    @TotalRowsToUpdate      bigint,
    @TotalRowsLeft          bigint
    


-- total row count to update
set @TotalRowsToUpdate = (select count(*)
                            from [Table1]
                                join [Table2] on
                                    btid = tBtID
                            where   btStatusID = 81)


set @TotalRowsLeft = @TotalRowsToUpdate
set @MessageText = 'Total Rows to Update = ' + cast(@TotalRowsLeft as varchar) raiserror (@MessageText,0,1) with nowait
print ''


-- begin cycle
while @RowCount > 0 begin

    set @Start = getdate()

    -- update packages
    update top (@ChunkSize) bti
        set btstatusid = 154,
            btType = 1
    from [Table1] bti
        join [Table2] on
            btid = tBtID
    where   btStatusID = 81
    

    set @RowCount = @@ROWCOUNT

    -- measure time
    set @End = getdate()
    set @Diff = datediff(ms,@Start,@End)

    set @TotalRowsLeft = @TotalRowsLeft - @RowCount
    set @MessageText = cast(@counter as varchar) + ' - Updated ' + cast(@RowCount as varchar) + ' rows in ' + cast(@Diff as varchar) + ' milliseconds - total ' + cast(@TotalRowsLeft as varchar) + ' rows left...'

    -- print progress message
    raiserror (@MessageText,0,1) with nowait


    set @counter += 1

    WAITFOR DELAY @TimeBetweenChunks

end

Resources:

Stack Overflow post on this subject (where SQL above was taken from): https://dba.stackexchange.com/questions/276314/how-to-avoid-table-lock-escalation